The only feedback path, as Ray says, is via a defective B+ decoupling.
But the caps certainly are for 'tone control'. This was pretty common, of course mostly in lower cost radios

with no tone control. I think 'shot noise' has enough low frequency component that this cap will have very

little positive effect on your reception. All I have said here is from my own experience as well as training.

Yes, L//C will create a frequency response hump, but as it's well loaded, I think the response is damped.
The Shure Brothers seem to have just told me the 'hump' will be in audio midrange, not the best for HiFi,

but maybe somewhat of a benefit for audibility, especially for voice.

Dried out or defective bypass caps are a common source of problems in audio stages.

-Hue Miller