This is very true and interesting. RCA figured out you could strap
the control and screen grids of certain power pentodes and use them as
low or zero bias triodes, and a couple of RCA theater amps do this.
This is also seen in AM era editions of the W6SAI Radio Handbook for
modulators. It is simple. It works. Based on long time experiments it
was concluded it doesn't sound very good at all.

I have never tried it, on the theoryu if it worked very well it would
be popular.

The 811 is certainly an attractive tube economically. It has a mu of
160 as I remember. The Altec 1570B used them as did the Gotham Audio
cutter head amp using a GR toroid for output.