> and even completely dropped support for them from their primary mobile browser for over a year now.
You're misinformed. Many extensions work, they are progressively being re-enabled over time, and on the nightly version they are all available, although whether they actually work or not depends on the state of the underlying APIs. The reason for the whitelist model, is that when they swapped to the new mobile browser engine, the underpinnings of many of the extension APIs had to be reimplemented, and they are not all online or bug-free yet.
The nightly browser, and the ridiculous[1] steps you need to take there to use extensions, are not their primary mobile browser. Installs from Google Play alone are two orders of magnitude apart.
And no, I don't consider a small custom list to be "support". It's a high-value list and a solid sign that they're not wholly abandoned, and I do expect it to come eventually, but it's very much not the same as general availability. General availability did exist before.
Edit: I broadly agree with their breaking of NPAPI stuff, WebExtensions (as a concept, not necessarily the specifics we have now) has a LOT of very real benefits, and does not inherently prevent equal or better capabilities. But it too is still a loss in control, as it stands today.
You're misinformed. Many extensions work, they are progressively being re-enabled over time, and on the nightly version they are all available, although whether they actually work or not depends on the state of the underlying APIs. The reason for the whitelist model, is that when they swapped to the new mobile browser engine, the underpinnings of many of the extension APIs had to be reimplemented, and they are not all online or bug-free yet.