Not at all. TFP is a non-profit, and all of us here are volunteers, we don't get paid. I've never met or talked to anyone from this site except through the site itself. Because of the recommendations here, I used Ahh-Some when we bought a house with a hot tub and I saw the results with my own eyes,
which I documented here with pictures for others to see. I'm assuming this is why it's "pushed" here so much. It works, and so we recommend it.
No. MA does not make the pH stabilize. What makes the pH stabilize is a TA that is low enough that offgassing does not raise the pH very fast. While I haven't read this entire thread, I skimmed the last few messages. You're correct that TA is a pH buffer, but raising it won't slow pH rise. I can try to find the post with the exact chemistry, but in short water with a high TA will have a pH rise caused by aeration. And aeration is something spas have loads of. So while the TA buffers pH changes, it also
causes pH rise when there is aeration. This pH rise slows as the TA is lowered, eventually usually stabilizing out at a TA of 40-50.
For spas where dichlor is often used, a higher TA can be of use, as dichlor is acidic and so counters some of the pH rise. This may be why the "industry standard" for TA is often quoted at 100 or so for spas. But too much CYA causes issues with chlorine keeping the water clean, which is why when following the TFP advise of ~30 ppm CYA and then using liquid chlorine to avoid CYA buildup a lower TA of 40-50 is needed since an acidic source of chlorine is not added on a regular basis.
Does this make sense?