Thanks for reply. I have said that I talked to one of the dev, and some others I wrote but not reply me yet. Seems that some of them are not willing to let the distributor selling their game as I know Mini Metro will end the contract and do it by themselves. I don't really think every one will care this issue as me, but it does make me feel important that maybe this thing will be getting worse in the future.
This problem is not really in the same situation of people who bought the games and sold steam keys. These company (maybe one to two is enough to be huge) would have much more resources than individual one, like you said, the players will be very often to see their products everywhere in itch.io, such as front page features or sales, bundles. If there is a player going to itch.io and want to pick up some nice indie games, and only can saw these big company's products at the first sight. And for my top worry, that they don't really be careful on managing their product own pages, that means the players don't have the same treat as in other selling platform, such as the update news.
I don't believe that when the free open platform grows, these kind of problems will happen, and we don't have any way to help. I believe that if every individual try to the best on the game and communication with players, these games should get more people to notice their brightness, so that is the reason I keep writing these kind of post and reply to let more people know and effect the itch.io manager's mind.