Although plausible, and part of it, it’s not just that. The second part is much more important (people unwilling to adapt), but one should think about why.
That’s the kind of stuff where companies & public administrations usually suck, “change management”.
I’ve seen Germany states jump into open source software strategies to later “regret” them and revert back to their previous state, many times… I hope this time they do it in a more thoughtful way, to avoid giving excuses to closed-source software lobbyists.
Their product offers many more features (and more complex ones) than the other services you mentioned. And they also took the time to provide a commercial product, with paid support, integrations…
This is key for companies, as it makes it easier to be productive, plus the SLAs give some peace of mind too.
Also people who left Twitter or never were there. Fostering radicalization while censoring legit links to other much more peaceful communities is going to increase social conflicts, and this usually leads to real violence sooner or later.