Server browser servers aren't invite only / whitelisted in any way for 99% of the servers.
The ones that are, might be set up for some kind of organized event such as a specific community event or tournament.
Normal, community-run servers are a great addition! If you can play within the same server, you're bound to make more long-lasting teammates, learning each others playstyles and how to synergize for better results overall.
On top of that, if we can judge by the PC servers or any other videogame which runs off a similar community-ran server scheme, it's that the community servers usually are more active in terms of events, as well as have better moderation in terms of getting rid of trolls, hackers and other types of malicious players.