mastodon.social is one of the biggest Mastodon Instances. It's the instance created and run by the creator of Mastodon but it's not to be considered the 'official' Mastodon Instance because every single Mastodon Instance has equal power to the others.
The optimal strategy for Mastodon is not to rely on a bunch of gigantic Instances but on thousands of local Instances.
Try to imagine to have at least one Instance for every city, town, school or workplace, with a LOCAL timeline and a FEDERATED one.
Thousand of Instances all connected together and wiyh the possibility to share informations snd block the ones that permits trolling, harrassnent or bad behaviour but giving to every single Instance the freedom to decide how to act.