@JohnnyCanuck is right in a bunch of important ways, but there is one additional factor to consider. The reason the Hollywood guild system works the way it does is because no one is contracted to any given studio. It used to be that actors and writers were required to have locked-in contracts - they couldn't work for anyone else - but that hasn't been true for a long time. (There are exceptions: writers and actors can choose to have multi-picture/script deals, in exchange for an up front wad of cash, but it's not the norm outside of the really heavy hitters.)

A standard union protects a worker's existing job, and helps that worker negotiate terms for an existing job.

A Hollywood guild protects a worker's future jobs - because the one they have now will absolutely not be the one they have in 2 years, a year, maybe even in 6 months. This is the nature of the Minimum Basic Agreement (MBA): it dictates minimum terms of employment. It's not designed to give writers/actors the best deal, it's designed to give them the least shitty deal the studios will agree to.

Why does this matter?

It matters because what most people think of as "Hollywood" is all the extremely pretty, extremely powerful, extremely prolific actors and writers who make lots of money and show up on magazine covers and in media podcasts. (No writer is showing up on a magazine, I don't care how pretty he is.) But the MBA is there for the day players, the low rung people, the staff writers, the gal who had one spec script produced in her career so far.

What the WGA managed to achieve recently with its negotiations is an absolutely phenomenal success. But it still only really impacts the MBA - the minimum basic agreement!

So… uh… why does this fucking matter?

The game industry doesn't really have superstars. It doesn't have the equivalent of Tom Cruise and John August. At least not at scale. And the ones who are that shiny are usually studio heads or creative directors, not "employees." So they wouldn't be covered by a union anyway (which cannot apply to managers - i.e. anyone who has authority over other workers).

Suggesting that the game industry adopt the Hollywood guild model is to suggest forcing a pear into a box shaped like an apple. The MBA protects low level employees in their future employment, and isn't really all that great - at least not the way most non-insiders think. It still results in a ridiculous number of workers making poverty wages.

Is that what you want a game voice actor to have? A minimum basic agreement for their future employment? A programmer? A graphic designer?

No. You want them to be in a union.[1] Which will protect their current jobs and create conditions for advancement, sufficient income at the lowest tiers and long term stability. None of which the Hollywood guilds really do.

[1] The distinction between a union and a guild isn't a "real" one in modern U.S. law, strictly speaking. But conceptually, as above, a union is for people in regular employment with a single employer, and a guild is for (effectively) contract workers. The terminology of "guild" came from the older, pre-industrial idea of "the X workers guild" (masonry, carpentry, bricklaying, etc.), which were really just social organizations that sorta kinda acquired enough power to flex their muscles against the people who were contracting them by having minimum demands in solidarity within the guild (does that sound familiar…?). Guilds eventually "became" unions in the modern sense, once people were working with single employers over a long term. Put simply (and a bit stupidly), unions make contracts between workers and companies; guilds make contracts between workers and their industry. Part of the reason gig workers (Uber/Lyft/etc.) in California have been more active about getting better terms is because that state is super familiar with how guilds work, which is exactly what gig workers need, since their employment is with the industry as a whole (they can work for more than one company), not so much with a specific company. (It's also why they're having a much harder time - because California employers are super familiar with all the shenanigans Hollywood studios use to suppress the guilds that feed into them.)