You don't need to know the new hot stuff if (a) you currently have a job and (b) that job is with an employer where people carefully think about their user needs, product goals, and then pick tech and write code with those needs in mind (much like the article recommends).
Otherwise, there's an extent to which you have to accommodate the absolutely rampant fetishization of current fashion for How We Do Things Now Because It's Better(TM) so you can sell yourself properly.
In more concrete terms: right now if you're looking for a gig as a front-end dev, you're going to have a much easier time finding a job if you can put Angular and React on your resume. The fact that this isn't particularly rational (or fair) as a hiring filter doesn't really matter.
If you're good at web development... that means you understand HTML, CSS, and JavaScript and you understand them at the level you should if you want to call yourself a web developer, then learning whatever framework a hiring manager wants you to know this week is trivial because you understand how the web works.
The problem is a lot of people just learn Angular for a gig. Then they leave 12-18 months later and go learn something else. It's never enough time to actually get good at anything.
And let me tell you... the hiring managers are taking instructions from development teams looking for talent. Those teams often inform management what is the hot new tech that needs to be used. But none of these things that people think they need to know have been so battle-tested yet that they are for sure the "next big thing."
I think experimenting is great. I don't think developers should worry themselves to death over having to keep up with whatever's new this week. I think devs would be better off investing that time in getting really great at the web. Really learn what semantic markup is. Really understand floats, clears, various display types. Really understand the fact that the web, without any JS or CSS, works great on mobile, because when it started, screens were 640px wide, and as a gang of developers, we've layered on boatloads of code to make it not responsive, only to make it responsive again. :)
And then, I believe everyone will be in a much better position to make informed decisions on whether or not "hot new thing this week" is really worth learning.
I'm a little puzzled about the "I disagree" part -- it sounds like you and I have some similar ideas about how things should be for front-end development!
Perhaps where we part ways is on the question of whether the industry leans towards sensible agreement. My impression is that it doesn't.
Otherwise, there's an extent to which you have to accommodate the absolutely rampant fetishization of current fashion for How We Do Things Now Because It's Better(TM) so you can sell yourself properly.
In more concrete terms: right now if you're looking for a gig as a front-end dev, you're going to have a much easier time finding a job if you can put Angular and React on your resume. The fact that this isn't particularly rational (or fair) as a hiring filter doesn't really matter.