Yes ... You guessed right. Biting..It has taken me a couple of days to sort it out, but I put it down to the more open SR.Tech.around 78...
I used to bite a very long time ago (and still do from time to time). I had noticed one day when putting the reeds back into my aluminum Rico ReedSaver that the reed was not flat. That it was more curved near the tip area.
This is when I started learning more about the curvature of the mpc rails, and that the curve can start at a variety of places on the mpcs. C*, C**, D, etc back then meant nothing to me except that it was harder to blow the larger the letters got for my alto sax.
But I noticed that I would bit on a C* maybe more than on a D. odd ?
Of course if someone plays a D and pinches alot they are essentially closing the tip and making it a C opening (for example). So one's tone can get more thin as they play more as the reed starts bending and closing up. I found this much easier to do on thinner cut reeds such as Hemkes than the Vandoren Traditional reeds.
One solution I had was involving the neck strap.
I would tightened the neck strap where it would pull the horn up and the position of the horn - ie, the mpc was so that it was pushing up on my upper teeth. This would free up my lower jaw.
Previously to that I found out that I was putting the mpc in my mouth and my lower jaw would actually push it up to my upper teeth. Thus creating an environment where biting was more commonplace. That scenario was probably better for a double lip embouchure.
I see that now on clarinet players as they bite up on the mpc and bring it up to the upper teeth. One reason I emphasis the right thumb properly holding the mpc up to the upper teeth. And then the lip actually goes out to meet the reed at a position closer to the section where the curve starts going away from the table, versus much closer to the tip where it can get closed up.