They really are playing different games.

To be fair, it's not really a binary comparison but more like a tiered gradient.

For the sake of illustration, lets do a mockup with some stereotyping (cause that's always fun!).

S Tier: Whatever is most effective and most consistent. They're not necessarily being a dick about it, but if they think a Doomsday deck is the best deck, they're going to play it, and if a turn 3 Doomsday win is an option, they're going for it.

Super Serious: Everything must be effective, but it doesn't need to be the most effective. Some consideration is given to avoid 'unfun' things, but the scope of that is a bit foggy.

B-List: I'm playing this because I like it, and I've got a plan to make it work. It may be good, but that wasn't the requirement or motivation.

These are the cards that I have: I hope this works, but I didn't follow a guide or read up on deck design. It's gonna take a while.

If you're playing against people in an adjacent tier, it can consistently feel like a good game. If you're playing against someone one or more tiers removed, it won't be.