I didn't actually say "they aren't fast, so they quit". I said people are giving up because they're not
as fast as others, which you and others have said is exactly what you are doing. (I don't consider myself to be "fast", for the record.)
The reason I said that is not going to help anything is twofold. One you've already stated yourself... the more people that give up, the smaller the grids get, and the less opportunities people will have to find people of their level to race with. Two, by giving up you are no longer practising or learning anything in this particular sim/club, so how are you ever going to get back into the fray with those that stick with it? You wont.
Anyone that has raced R3E for the last couple of years will know that I didn't used to be a top-five finisher on a regular basis. I routinely found myself in this so-called "no man's land" hotlapping on my own. But I stuck with it, I asked questions, I watched the faster guys, and I learnt new things. Put all that together and I'm a better driver and can now fight with the "big boys" in many races.
So the fact is that there is only one solution to this "problem", and that's to stick with it, learn from others, and eventually get faster. The ball, as they say, is in your court, because becoming a better driver is down to the individual, not RD.