TFT is one of the most popular additions to one of the greatest MOBA of all time, League of legends. But unlike many other companies that make the same game over and over again, RIOT has introduced a completely new design to the mix.
And that is why TFT is far different than any other MOBA and does not give EXP? Why do you ask?
It is because of two specific reasons.
Reason 1: We try to grind the game to level up by gaining EXP. In most games the more you play the more you level up. And that is why many players just go into the game and want to get it over with as soon as possible.
This kind of mentality is very bad for a new player base. And it also harms the gameplay of other players. Keeping that in mind, RIOT is rewarding their TFT players with pass and many other ways to get their hands on the emotes and characters. That is why giving XP is not necessary.
Reason 2: Another big reason for not giving XP is the new release. As a new game, the company needs more data on multiple variables before determining how much XP should the player get for each occasion.
For instance, if the game goes longer than 20 minutes, or how long each game takes to start. How many matches are played on average to finish a game? Riot does not want to make a decision based on assumption. As a result, they are not offering XP for TFT games.