ransley full-quoted:

The real gimmic are the fiberglass filters that let 95% of dirt
through and degrade system performance by clogging up coils. My
neighbor had to remove his AC coil one winter, he got no heat it
was clogged shut, next spring he power washed it.

I've often wondered why today's so-called high-efficiency furnaces don't
include a seasonal bypass duct so that during winter operation air can
flow around the AC coil instead of needlessly being forced through it.