Need more info. e.g. Event on that delivers points for every troop of yours they kill? (However few those points may be.)

Trite answer 1: Why not?

Trite answer 2: Because they can.

There are many bullies out there, and a larger one is often just around the corner. They just haven't noticed you. Yet.

That's life. Figure it out. Determine what works for you.

Sadly, many don't care that hitting you brings them no points. e.g. Hitting a non-OvO opponent during OvO.

OTOH - there must be consequences for poor behaviour, lest it repeat.