The issue with the "proof of work" standard is it sets up a difficult conundrum. You need to work to join the guild, and you need to be a guild member to get most work.
It’s great when you’re in but if you don’t have the connections to get in you can find yourself on the outs for years.
If a SWE guild can find a way to eliminate the nepotism and create a meritocratic way to get into a guild…
But the number of times I've heard directors and such tell stories about how they wrote a line for a non-speaking part as a favor to the actor in the role, solely to allow them to get their SAG card, is disturbing.
It's indicative of a high degree of gatekeeping.