Credit card spend isn't the only way to earn additional LP, and for many people likely not the best way to earn a lot of LPs (opportunity cost).

My guesstimate (that I use to justify my AA experiment) is that I will comfortably be able to reach AA Plat status and likely AA Plat Pro while on AS I would struggle to get to MVPG. It will involve some otherwise unbonused credit card spend, but also AA Hotels spend when earning AA miles and LPs is more attractive than earning in the hotel’s native program. A lot of my hotel stays are in HIX/Hampton Inn/Hyatt Place/Doubletree/Courtyard style properties where hotel status is fairly pointless (pun not intended). And there are also SimplyMiles and AA Shopping offers that can add the equivalent of a transcon worth of LPs for something I might buy anyway.

As for upgrades, since most of my AS flights go through SEA, my upgrade rate as an AS Gold or 75k has been fairly mediocre, so not sure I will miss that much. Might be different for the OP out of SFO if they get to AS Gold or higher.