That’s a legitimate decision responding to their environment – you might disagree because you have different goals and resource levels but it’s wortb understanding why not everyone makes the same call.
I do frequently. There are many things in life that are hard and cross-browser CSS is not among them.
In the past I have found things like Bootstrap and jQuery to be more of a frustration than a benefit by introducing cross-browser differences in their attempt to help. At the same time they don't fix the cross browser differences that really impact layout, such as differences in font rendering.
And jquery support often isn't necessary at the moment. It's required for some functionality, but many simpler web pages will work with a slim version of the CSS without any JS. Makes it very light-weight and still easy to set up.
All the utility classes are useful too.
Why waste time creating all those components manually?
Also as you say it's still great for prototyping and internal applications that don't need bespoke styles.
It’s just nice clean flexible sass to start from.
I prefer a 24 col grid as well which takes about 4 lines of sass.
If you're building Facebook, yeah maybe it's not so useful.
The layout support in Bootstrap is nice, but the baseline design language is more important
My reason for using bootstrap is that it looks better than any UI I design from scratch.
"because that is what they know and don’t bother picking up the new standards"
That's just an unnecessary comment and plain wrong.
Nevertheless, recently I tried spectre.css [2] and liked it a lot better than bootstrap as it doesn't feel so heavy (don't know how it performs in terms of browser compatibility).
If your application has many basic views, you'll be wasting time writing out CSS grid properties for a basic responsive layout.
I mean, at some point you'll recognize you're reinventing the wheel and just pull in a CSS grid from a framework.
This applies to basically any components that has been battle tested in Bootstrap.
I'm not saying that everyone should use Bootstrap, or even CSS frameworks in general, but this idea that we should avoid them because don't 100% require them is madness. The simple reality is that they save a hell of a lot of time that can then be invested in things that'll have a more material improvement for the end user.
I see no reason for using a third party layout system now that CSS has `display: flex;` and `display: grid;`. As for modals and menus, HTML has `<dialog>` and `<details>`. And for reusable components, we have custom elements, that you can either implement your self (not that hard) or pull from a library (using javascript modules).
Really the only reason I see anyone using CSS frameworks like bootstrap is for quick prototyping or because that is what they know and don’t bother picking up the new standards (which is ironically where jquery was a few years ago).