Professional grading companies like PSA (Professional Sports Authenticator), BGS (Beckett Grading Services), and CGC (Certified Guaranty Company) evaluate cards on a 10-point scale
Some players want the challenge of building a Brawl deck using an unconventional commander, others want to lean into a Universes Beyond theme, and some show up to showcase their skill and knowledge of the competitive metagame
Theres also the subgame of Who can cast their emerge card first? Games where both players are utilizing emerge cards will often come down to tapping out your opponent first with Elder Deep-Fiend and then following that up with another Deep-Fiend if you were able to search one up with Sanctum of Ugin or just naturally drew one
Better yet, when you sell on those platforms, you can leverage tools like PayPal Goods & Services, whose 3% fees are a far cry from eBays brutal ~14% (as of 04/21) managed payments fee in the TCG category
You get the mana immediately and dont have to wait to meet a condition