Is it true?
Does it really matter?
Would love to hear opinion of experienced developers.
Is it true?
I feel that they are on their way out but still used by PLENTY of companies in their production code. There are lots of job postings that still list jQuery as a nice to have or required skill (in my area, at least).
Bootstrap is slowly being phased out by flexbox, css grid, etc.
jQuery by various frontend frameworks like react, angular2, JS is introducing fetch() etc
I would still learn them as they don’t take a long time to get a basic understanding of and it can’t hurt your job prospects
If it matters? Ultimately no, you should be capable of using raw CSS/JS either way, these tools are just means to make your life a little easier, not a necessity.
If bootstrap makes your life easier, use it till the end of time. You should mix and match between these tools to see what works better for your development environment, it’s irrelevant to question what is outdated or not in this manner.
If you want a specific job, just go on job boards and see what companies are asking for in your area. They might be using bootstrap in your area. Or maybe they never used it.
Here where i live bootstrap and jquery are essential, and so is java EE 6 and .NET. This is not a reflection of the market worldwide, and it shouldn’t be reflective of your city’s reality. The only way to know is to research on your own.