I personally despise internet abbreviations such as "gg" or "hf" (good game/ have fun, respectively).
Perhaps it's just my strong attachment to formality, honor, and respect, but I always say, "Enjoy the game" or at the very least "Hello", not "hf". At the end I always say "Thank you for the game," not "ty" or "thx". I also thank someone for the review the same way I do a game.
What are some other people's views on this topic?
You just can't expect, let alone enforce, elementary manners on the Internet, more so since manners are not universal. Live with it or build your small circle of opponents and make appointments.
I know, I know. Blitz matches obviously don't count, and I know I can't enforce universal manners. This is why I'm not really upset about it, and why I'll never tell someone in a game, "you shouldn't abbreviate!" Its just a little quirk of mine.