The answers to your concerns is very simple, and it's nothing other than hype, solana is currently hyped as the top blockchain where there is enough liquidity for memecoins, so so, it so normal thing for memecoin developers to rush there to have their own slice of the cake.
Think of it this way, the moment a developer creates on a particular blockchain (as it is in this case with Solana) and it succeeds, and another developer comes and do the same thing, and it succeeds, and up to 10 developers try the same thing and they all succeed, rest assured that alot more developers will start rushing to create it build on that blockchain.
It's like playing a particular slot game in gambling and winning huge, tomorrow, you are going play that same game to see if you will win again, and if you win, you will definitely come back again the next day, and the next, and the next, and your friends, and other persons are also going to start playing that game too, as long as the winning continues for the majority playing that particular slot game, that is hype at work.