The turnover for games, GMs and players seems really high here. But I do not think it's higher here than anywhere else.
Personally I've been heavily involved in several games, both as DM and Player. Currently I'm only in 1 game that I both Narrate (I prefer "narrator" to dm/gm) and have a PC in which has been running since April 2017 (3 years last month). It's a Ptolus game (
https://ptol.us) with 5 characters all controlled by 1 player. Then I have my DM PC and dozens of NPCs.
We are multiple times per day posters and communicate outside the website almost every day as well. We found each other on the site, so not previously friends.
All the other games died b/c people simply disappeared (stopped posting), or I quit because there was weeks between posts, which simply doesn't work for me.
1) I think the best way to be successful on this site (or in any D&D venture) is just to
make sure you manage expectations. If you're the DM and you want daily posters, then make sure you advertise that and setup that condition from the beginning.
2) The other thing you should do is simply
prepare for disappointment and attrition. Life happens. People lose jobs, get sick, die, have babies, etc... Players are going to leave your game, just prepare yourself for it. DMs are going to ghost, make sure you or someone else has access to DM the game so you don't lose it.
3) Establish communication outside RPOL. I don't know how big a deal this is to anyone else, but I've done it now with several people from RPOL and it's certainly helped. There are a billion ways to connect with people, so find the one that works best for you. Discord channel. Email. Whatever. This will also allow you to connect if someone ghosts on rpol just to ask, "are you dead" b/c push notifications aren't available on RPOL, yet. :D
Anyway. I hope you find what you want and stick it out. RPOL changed my life and I absolutely love this website and play by posting.