Cool topic :whstlr:
Guess I'll add my opinion!
1) Simply because you immediately feel that every single member of this community has the greatest interest in taking care of their aquarium. They do not try to sell you stuff you don't need, like shop owners would, as after all shops are and always will be about profit. This is why this is such a great place to come too. Legit advice to base your research on, without having to be suspicious if the info is correct.
2) Mods are just... dunno the proper word for it ... "heavenly"! I mean, go to most(not gonna say all as there are some exceptions ofc) other forums and you will see admins and mods trying to be cocky know-it-all's. Here they treat you like equals, help you as much as they can and best of all, they keep it up over the months/years. Most take it for granted that you're always nice to people, but having been a mod myself(on another forum), it's very very stressy sometimes! So props to them rly for keeping it up!
3) Last but not least, the forum stays active. You won't find many threads that didn't get an answer. No matter how stupid your question might seem, someone always tries to help you out.
In short: There is no better place in heaven or earth for your aquarium information