I agree with Cedric, I think there shouldn’t be many tribes or they would become a confusing feature.
I believe they should not exist just because they have enough members, but TR should choose them considering the specific need of filtering out searches (which is the main reason they exist, am I wrong?)
Therefore, in my humble opinion, TR should create a new tribe only if it helps people at filtering a target for specific and practical reasons.
For example, I think “travelling girls” (or a fun name like “girl power”) would be super useful for girls looking for women hosts. At the same time, a tribe like “Spirituals”, which I am a proud member of, is probably not a useful filter and could even be safely removed in the future.
This is just my point of view, I am confident that any decision will be ok because the only important thing is to create a positive, creative and welcoming community.
P.S. If you let members create tribes themselves, you must be prepared to see titles like “Scottish”, “Hungarians”, “Italians” etc. Some new tribes could be about politically divisive issues, like “Proud to be Catalan”, “Leave EU”. Do we really need them?