[Antennas] Only dumb question is the one not asked

[Harvey&Bessie]

The impedance right at the feed point is (when SWR is low) close to 50
ohms. the coiled co-ax near the feed point forms an RF-choke only for
the outer conductor (the field of the inner conductor is entirely
contained within the outer conductor acting as a shield) so, the RF
"seeing" a higher impedance (several hundred ohms) in the path down the
outer conductor, as compared to the 50-ohm impedance of the inner
conductor, does not travel down the outside of the outer conductor.
As for connecting a "ground" directly to the outer conductor at the feed
point -- how would you propose doing that? The antenna, hopefully, is
elevated some distance from earth -- the source of any true ground
connection -- any wire lead you connect there has to have considerable
length to get to "ground." It is still ground for DC, but not for RF. In
fact if it is exactly (or nearly) one-quarter wavelength long it is no
ground at all but an open circuit at RF!
Harvey/W4TG