Maybe you weren't pubstomped, maybe you're just a scrub?
I have only played a pubstomper once. They sat down with Rog-Si to a bracket 4 table on xmage, claimed the deck wasn't that good, and went offline when challenged.
I have met tons of scrubs however. Players who when playing against decks built to the restrictions of the bracket we're playing in, or when previously playing in a 'high power' magic game or whatever became extremely salty when they encountered a particular style of play (wheels with Nekusar once induced a ton of salt I recall).
I remembered this article recently, and thought this perfectly summed up the mindset of many players who claim to have been pubstomped. It's worth a read.
https://www.sirlin.net/ptw-book/introducingthe-scrub
I think ultimately there are some players who approach EDH, especially non cEDH with a scrubby mindset, and others who want to try and win the game. Whenever these players meet, it will always feel like a pubstomping to the scrub. The more competitive player will exploit synergies in their play that the scrub simply doesn't consider. Sacrificing in response to removal, tapping mana correctly for spells, casting spells after they have attacked and even casting instant speed interaction when it isn't there turn and using it effectively after correct threat assessment. They might even have the win in hand, but wait as they can see signposted interaction, and will wait for a shields down moment.
I'm 99% sure the problem isn't pubstompers, it's scrubs.