I mean I don't believe its begging. Begging would be spamming please play my game in every games comment section. Both parties are giving each other feedback on what to improve. Sure you can make the argument its begging because its forcing them to rate your game but the person who made the post has made the decision that they would be rating games and giving feedback and the person replying has as well. Its the same as if both people had the mind set of I will play all games from people who comment on my game which a lot of people in the rate for rates have as well. Just this is a way to guarantee the 20 rates. As the moment this is basically the only way to guarantee that for those that dont get lucky with ctr, dont have much time to commit to ratings, or dont get lucky from the games they choose to give feedback on.
As the mechanics in itch.io exist currently there will always be those that are screwed over by the current system even if they give feedback on others (and for those who cant give feedback that well and can only rely on people to use the random sort, it never works out unless they have a great thumbnail)
The way to stop it would instead give some other way for people to get a guaranteed number of ratings. The system in Ludum Dare is miles better than what exists here and theres absolutely 0 rate for rates because of it. In ludum dare the more good feedback to others you give, and the more games you rate, the more your games gets recommended to others with the things you do having reduced effects the more you do it (so that people tend to get 20-30 ratings and not much more unless they're extremely dedicated with giving feedback or get snowballed). This means you have the community aspect of going around and rating + giving feedback on random peoples games and a lot more people use the random sort because theres a lot less possible risks to doing so