But it is right. If you an't explain why something is then it isn't. Not in any objective way.
While fun is overall a subjective term, on an individual level whether or not something is fun is objective.
The Pokémon TCG, for example is not fun to me. Why? Because it just feel too random to me. Too many literal fucking coin flips and shit. Meanwhile the TCG game for the GB/C is fun. Why? Because while the RNG is still somewhat there, you can control it to some extent.
The game auto-quicksaves during battle but only at the beginning of each of your turns. This means you can reload and start from either the last save point OR the beginning of the last turn of the duel you were last in. For example, use the Poké Ball card and get tails? Reset and hold on to the card to see if it works out next turn.
Depending upon the context they could very well be correct that it's being used as a buzzword.