Because the reason companies are brazen enough to pull the crap that they do is because most people have viewpoints along the lines of this post. Reddit for example has almost certainly performed a cost-benefit analysis and wouldn't have locked down their API like they did if they suspected an actual risk of enough people switching to Lemmy and other alternatives where the lost revenue would have been significant. And they were right, the vast majority of Reddit users tangentially looked at Lemmy and similar alternatives but are still on Reddit. The people actually here on Lemmy saying they'll never use Reddit again are a tiny minority of Reddit's total userbase.

I'm genuinely surprised that a creator who has a ton of op-eds in his videos and constantly pushes for electrification and heat pumps citing their lower environmental impact, which is very correct and noble of him mind you, doesn't apply the same logic to software.

Also, obviously it's not good to be a dick when promoting FLOSS as you're more likely to push people away from it, if that was his point then I'd tend to agree (admittedly I've been guilty of that before). Maybe that's what he meant, but he doesn't mention that in the post and seems to imply that even a friendly or matter of fact suggestion that a FLOSS alternative is available is unacceptable. Like are you complaining just to complain or are you complaining because you want suggestions on how to solve the problem? I don't know what his experience with FLOSS discourse is, but I've personally complained about a proprietary software, had someone point out that an alternative exists, and immediately tried it out and often end up switching. Literally the other day, I was complaining about the Unix cp command, someone suggested I use rsync instead because "it's better", and what do you know they were right.