I think it's fair to say the situation is even more complex than that: being a W3C Member doesn't necessarily mean they've really had anything to do with the standard, as the majority of Members aren't in any given working group, and even then, the majority of members of any given WG scarcely participate. (For the sake of clarity going forward: a "Member" is a W3C member organisation, a "member" is a member of a given WG who is either a representative of a W3C Member or an Invited Expert. Yes, this is ridiculous.)

The HTML WG was merged into the Web Apps WG in 2015 to form the Web Platform WG; previously, the HTML WG was rechartered in 2007 to work on HTML5 (the previous WG of the same name had been working on XHTML2), with a novel experiment within the W3C, heavily influenced by the WHATWG: allowing anyone who agreed to the IP policy (essentially, an irrevocable patent grant unless you explicitly mentioned a patent you held within a certain period) to become an Invited Expert (under the somewhat nonsensical term "Public Invited Expert").

This WG fairly quickly became relatively unworkable (people refusing to listen to other's arguments, being completely unable to come to consensus on a number of issues, a habit of subgroups presenting things at fait accompli and then failing to accept there might be any flaws in their work, an ever growing number of ad hominem attacks, and general interpersonal nastiness). Eventually, all the browser vendors essentially went back to doing all the work in the WHATWG leaving those not directly involved with web browsers to work on the W3C spec. Many of the historic arguments were clashes between what browsers saw as workable v. theoretical purity (and yes, this is reminiscent of HTML5 v. XHTML2, again, and that's with web developers within the WG), and with the browser vendors gone there's little opposition to most of what is proposed, and hence there's relatively little debate about much of what's done. As more time passes, there's ever less opposition. There's far more debate over features within the WHATWG, but also far more civility.

This all said, it's been possible to contribute to many W3C standards while not being a W3C Member or WG member for years, by simply contributing to the mailing list or more recently GitHub (this is typically only complicated for employees of W3C Members whom aren't permitted to join the WG by their employer). If web developers want to get involved in groups at the W3C whether that's HTML, Web Components, or CSS, all of which are primarily worked on on GitHub nowadays, I encourage you to comment on issues, or file new ones! There have definitely been people who have become Invited Experts through such actions, and some who have been hired to work on standards as a result, and on a personal note I can attest that the CSS WG is a nice, functional group, full of nice people! (I've been a member on-and-off since ~2010, originally as an Opera Software rep, nowadays as an Invited Expert, with a period of being neither inbetween.)

At the same time, much of the power of the W3C is held by the Advisory Committee (and, mostly theoretically, the Director, TimBL) and that's formed solely of W3C Members (people who are Invited Experts have no say here!), with votes needed both to start working on a new area (e.g., restarting work on HTML) and advancing a spec along the Recommendation-track. It is there the Members have power, and all are considered equal. There are plenty of cases the first time a Member really gives any statement about a spec is just before it gets published as a Recommendation, and really at that point it's too late unless the objections are really fundemental.