Not sure that's a feature.. Why would you want to reset your game?
Some people waste their money, make bad purchase decisions, accidently sell the wrong item etc, and end up with at a high exp lvl, a low mech level, and no money.
And the recent update has made things worse with the min-vslvl20 for high explvl players.
For example, say someone has vs-lvl=14 (slow at upgrading mech, due to wasting money on kits and such) and exp-lvl=24.
When they get their next level up, (to exp-lvl=25), they will start facing lvl vs-lvl=20 opponents, in battles they can't hope to win, having only a lvl=14 build of mech.
So with no money, and being severely outclassed, they can either keep fighting (and losing) saving up the pittance that you get from a loss, and eventually upgrade their mech to lvl 20 after hundreds of matches of constant losses, they can quit the game for good.
But that's just one possibility (though unlikely/rare).