Everything we've seen about this program indicates it is implemented as a blacklist of undesirable behavior and not a whitelist of known-good as formats. For your first example, the difference between this being beneficial and problematic comes down to the guidelines in place.

Note a similar FUD argument can be made about Google's own advertising network: "if we unilaterally decide we don't like your ads or your websites we'll cut you off." Similarly for search results. Yet Google's implementation and guidelines are generally seen as reasonable, economically satisfactory, and not stifling innovation.

Also, what would be the point of dropping out of this coalition? The online ads industry is largely self-regulating, there's no federal regulator setting the rules. Instead coalitions like this one are formed which set guidelines and make standards. What point would it serve to pull out of a coalition and subject yourself to the control of your competitors for a one-time show of goodwill at the expense of long-term influence?

Maybe you don't trust self-regulation, and that's fine. Appropriate even, given how often it breaks down. But keep in mind the alternatives are either government regulation or no regulation. The advertising industry is presented with an existential challenge in the form of bad advertising and ad blockers. The closer you look at it, the more you realize this move is actually a pretty good one, all things considered.