Critical mass of users on social media platforms.
Back on Usenet decades ago they called it the "Eternal September".
It used to be that every September, fresh University students would gain access to Usenet for the first time, and there would be a rough adjustment period where they don't yet know the ropes, the lingo, the etiquette, the unspoken rules, and the expectant decorum, etc. Then one year, home internet service providers made Usenet accessible to ANYONE who subscribed... And from that day forward, it was like September every day, all year round.
Now the general riffraff are flocking to bsky because even THEY see that Twitter is sinking. This surge of new users have brought all their bad habits with them. Bsky must adapt or it too will fall.
Yet another case in point of how shitty mastodon's name is. Even its abbreviations are trash. The best time to change its name was before it started. The second best time is NOW. And the longer they go without fixing this, the worse it will be. As long as mastodon never rebrands, it is doomed to fall behind scummy oligarch controlled trash like threads.