>>58499136+20 in every stat was the best GF's game designers could come up with after 12 years since megas originally debuted
Prease undastand
>>58499167High BST does not mean SHIT if it's not distributed well or on a mon without good abilities/movepools.
On top of meh stat distribution, this takes up an item slot and your team's opportunity to use a mega pokemon; when there's plenty of existing fire and normal types that benefit much more from mega evolving than just a +20 to every stat on a mon with a mediocre stat spread in the first place
Also even by mega standards, 607 isn't anything to brag about
Meanwhile pseudo legendaries have high stats (and often actually specialized so they can do at least a few things well) without needing to hold a specific item or take up your team's mega slot, and also at least a few of them have more than one viable ability option