You can see your total collection value change month over month, identify which cards are dragging performance down, and make informed decisions about rebalancing (selling deprecating cards and buying appreciating ones)
Sure, experience counters require deckbuilding and play constraints (ignoring creatures die I guess), but Commander players jump through smaller hoops for less
Not because Dragon Rulers were powerful, which they clearly were
If you know you want to build a Planeswalker-heavy "Superfriends" deck, going to the Planeswalkers theme page shows you that Atraxa, Praetor's Voice, Carth the Lion, Esika God of the Tree, and Sisay, Weatherlight Captain are the most popular Commanders for it, while cards like Oath of Teferi and Nicol Bolas, Dragon-God are the most popular cards in the 99
Even gave me some free sleeves for my cards