As a Druid main, it feels to me a lot like it might feel to a Warlock main if they just removed all the invocations involving Eldritch Blast, and removed Hexblade armor proficiencies entirely. Imagine if then you had a bunch of people on the forums defending these changes as "the right direction" because there are all sorts of "busted" builds that use both of these things.
Druid "main"? You're taking me back to WoW raiding ca. 2006.
Anyway, your analogy is most applicable if the issue is really "broken" builds. But I don't think it is. I think it's about system mastery and trap choices.
Since you have me thinking about WoW (and because you said 'main' I suspect you'll know what I'm talking about, but maybe not) at some point back in the history of WoW...I honestly don't remember which xpac...they got rid of talent "trees" and turned it into a tier model, where every X levels you picked one of three talents ("feats"), each of which had a different flavor, but were meant to be roughly balanced, if useful in different situations.
A lot of self-professed "hard core" players kicked and screamed about "catering to casuals" because no longer did gameplay superiority require understanding the complex interactions of the talents, and the math behind them.
The reality, of course, was that most of the players who were upset didn't actually understand that math, or do the work, themselves. Everybody who was at all serious about the game Googled the best talent choices and used those. And everybody who wasn't serious (or who hadn't learned about this yet) picked the wrong talents and sucked. Which the serious players loved because it allowed them to WTFPWN the noobs.
With the new talent structure the delta between those who Googled talent choices, and those who just picked their own, was greatly narrowed.
So getting back to the 5e Druid: as it stands now, players who pore through the Monster Manual comparing stat blocs for CR 1 beasts...or read a blog/watch a video about how to Druid...are vastly more effective than players who like to pick different beast forms based on story and whim.
The Warlock, on the other hand, doesn't suffer from this. Or suffers a lot less. A Warlock who picks non-EB invocations won't do as much damage, but the invocations they do pick will let them be good at the things they care about. Also, in order to compare Invocations they don't have to do research in a book that really belongs on the DM's side of the screen.
(It would be interesting to cross-correlate posts and see what % of the people who like the Druid as it is also think it's evil metagame cheating to read the MM.)
TL;DR: It's not about nerfing OP builds, it's about reducing the effectiveness of system mastery.