I didn't look at Bowser in a vacuum, I criticized his gameplan. It centers around his grab the exact same way as Luigi's did: it's his best way of doing damage at low percents and his best way of killing at higher percents. It wasn't abused versus a Rosalina because she's probably the worst character to perform grab setups on due to her floatiness and Luma interrupting you.
Also (
Jams.
as well), Bowser never having the same effect on the meta as Luigi did is a brave thing to claim, especially right after a Bowser beat players like Vinnie and Void (and almost Ally) and got 4th place at a tournament that was stacked towards top 16, something Luigi hardly ever managed to do. It already proves that the character is able to do it. Meanwhile DK has been contesting top players and characters for a long time through a few notable players.
The fact that their weaknesses are more exploitable than Luigi's might be made up for by the fact that their grab setups kill 50% earlier and that they live far longer, benefiting more from rage. They are undeniably more extreme than Luigi
in both directions and we can't pretend to know how it all pans out when the characters are put into actual effect.
Either way like I said, even if this is not the case, you'd only be allowing DK and Bowser to have a super explosive and simplified gameplan because they're not that good regardless.
But a character can be badly designed without being good. I once made an example that, if there's a character who has mid to low tier tools but has a 10% chance to automatically win any match as it starts, they'd be straight up cancerous to individual players in a bracket, yet they could never win any sizeable tournaments. The same way Bowser for instance might never be able to win anything big, but he can beat any player by guessing right a few times in 2-3 consecutive matches, just as he could always be beaten by anyone doing the same thing. Even if the opponent always has better odds for this, no one wants a match to be decided based on just a few exchanges per stock.
The only opposing arguments left are: "Bowser doesn't rely on grab that much" and "Bowser can't take a stock off reliably with just a few guesses", and both of them are straight up untrue. He relies on grab more than anything else because the risk reward ratio for it is completely twisted (the fact that grab isn't the only move he ever uses or even 2/3 of the moves he ever uses doesn't mean he doesn't heavily rely on grab). He can do 20-30% damage per grab easily, and he only needs 70-80% to take a stock off in most cases. For DK, this is even worse because his grab is better, he can do more damage per grab, and he kills with it earlier.
A match decided by only a few exchanges is uncompetitive. One tool being the optimal choice over all other tools in most scenarios is bad moveset design. DK and Bowser can take a stock off
consistently with only 3-4 actual neutral wins. And they do most of it with one move.