Quickleaf
Legend
That is absolutely not satisfying when you're trying to make a new and unique monster. Not even a little satisfying.
It might work for some dms, but not for those who like to add new stuff to the game that isn't the same as the old stuff.
EDIT: Also, not everyone uses dndbeyond, and the game should not assume everyone does.
Heck, half the time I don't even use stats for a new monster. I just use an old one and add things without the math. Being off a point or two has no effect on the fun.
I've had situations where both of these approaches had their place.
A spitting mimic? I can add acid splash or something to a mimic, done!
A high CR complex undead that inflicts a petrifying disease, then animates petrified victims to fight for it, and can also teleport into your armor (teleporting you out of it) like a heat-seeking missile? OK, yeah, I'm going to need to roll up my sleeves and really get to work!
I do think the DMG (or MM or whatever) must accommodate both methods, and right now we only see accommodating the former. I know someone raised a counterpoint, but my opinion is that not too many pages are necessary to provide a better starting point for more nuanced customization. I don't mean Tome of Foes level options (just get that book!) - just the starting point. I suspect I could do it in 4 pages.
You know, maybe I should post my own method in a separate thread!