Bootstrap is still one of the most popular CSS frameworks to this date, so it makes sense to to learn it and use, as other will be able to work on it too without a learning curve.
As for jQuery, it solved a lot of issues with old browsers, especially compatibility issues. But JS has learned and improved over the years. I think it can be helpful to know a little jQuery so you can use it, but knowing how it all works under the hood is far more valuable IMO. If you become well-versed in vanilla JavaScript, then you probably won't need jQuery anyway. And besides that, you'll have a solid foundation for any other framework that crosses your path.
If you think the article presents incorrect information or if you have an opposing viewpoint to share then please do. To your point, of course we think Bootstrap is still relevant, and we have built our livelihood piggybacking from the framework.
Of course we are bias when it comes to analyzing Bootstrap, but nothing in the article is false or misinformation, it's simply a sharing of opinions which is open to criticism. Millions of people have used our site as a resource for years and years, so it should come as no surprise that we support the framework.
As others have said, make all the hard stuff is CSS first, I just used Bootstrap for the first time and it’s saving me a ton of time.
Like you should know what CSS creates an hamburger drop down from scratch. You should understand how REM works. And especially learn how FlexBox works.
That said it’s more helpful to write your own classes and your own css first, but once you understand that it’ll help a lot.
It made me appreciate Bootstrap a lot more when I was asked to build mobile , tablet, and desktop responsiveness based on a Figma sketch. If I had handwrote the css from scratch it would have taken forever.
I have used bootstrap extensively on some projects, and on others not at all. It's really just one tool in the toolbox; sometimes it's useful and sometimes it isn't.
But if I take your second question a bit more literally, I would say yes, keep learning it. Here's why:
Since it's a widely used and tested library, with lots of contributors and reviewers, there are a lot of practical architecture/design choices that you can learn from if you take the time to read and understand the actual code [and even the issues that lead to them]. In addition, it offers some very thorough and relatively clear documentation. It's also very extensible and at the same time granular- using a pre-processor you can compile just the modules and components you need.
If you're working with a team, especially one with varying levels of skill, all of these attributes are valuable and important to understand. Especially so if you're going to "roll your own framework". I can't tell you how many times I've had to work with in-house frameworks that have no forethought, granularity, or documentation. In nearly all of those cases, the resulting homemade framework ended up being virtually the same size as bootstrap, with essentially none of the positives.
In short, understand how bootstrap is designed, and you'll be in a much better position to decide when it is and isn't right for a given project. And you'll also understand better how to create an alternative when needed that is robust and usable.
Worth noting is that these component libraries [including Bootstrap, as it also exists as a component library] has a documented API with the used SCSS- or CSS variables, classes and how you can customize each component in detail. For example, all of these templates uses Bootstrap but they look very different.
Meaning you could still use a component library to leverage some of the more complex components, while changing theme to keep your apps from looking as default. Most businesses has their own color palette which is easy to plug into any component library's theme provider.
One thing about component libraries though is as soon as the client needs something that isn't supported out of the box by the library it could cause a lot of pain to resolve.
It's crazy how the frontend moves so fast compared to backend technologies, which still uses SQL databases from the 80's. Even though they have of course improved. I just learned about react-query the other day and it blew my mind how much simpler it is to work with state from the server now.
It is good to know how to use, and there are a lot of reasons to use it for professional work [you can work with others or pass work off to another front-end dev more easily than if you custom-built everything, and it is faster/easier than reinventing the wheel every time your client decides they want modals, etc.]
That being said, I wouldn't rely on it for personal/portfolio projects. If I were looking at someone's portfolio, and every site was bootstrap, I would not feel very confident in their CSS skills [unless they had done a lot on top of the bootstrap]. Also, it's more overhead than you probably need [i.e., don't use bootstrap if all you really need is a grid].
I treat it much the way I treat JQuery [and I use both in my job now]--make a couple simple things with it to get the feel of it, but don't dedicate a huge amount of energy to Learning Bootstrap/JQuery inside and out.
Both of them have phenomenal documentation, so as long as you have a rough idea of how they work, you can easily figure out an individual part of them later when you get assigned to a project that uses them.