On Reddit I mainly participate in the subreddit for my town. The town subreddit has 50,000 members; the town plus neighboring towns has a total population of about 900,000. How will you get enough participants for it to be worthwhile for me to switch?

r/Compilers has about 14,000 members. Again, how will you find that many people willing to contribute on that topic to make it worthwhile?

r/ProgrammingLanguages has about 90,000 members.

You have a chicken and egg problem -- until you have enough actively participating members, there is no benefit to moving.

Unless you don’t have anything indicative of a community already in place then this isn’t a sound enough motive.