Yes -- I have made many many quilts before/without a walking foot. With my vintage machine I typically left the feed dogs engaged even, but it was (is!) one capable of doing jeans and upholstery. I was limited with what I could do well but with a lot of fabric turning and such could do straight grid lines on the bed (or I call body) of the quilt. Could do a bit fancier things and gentle curves like pumpkin seeds on the border. Borders were about the number of passes... 2 didn't seem enough, 4 was usual and I got bored with much more than that.
Having said it's possible it is -- but at this point in my life I do not want to stuff a king sized quilt through my vintage machine again, and my body just can't handle the effort without being "crunkled". Plus although I still want a lot less quilting that is popular today, I do want more free motion than grids and things I can do with my feed dogs up.
Getting a walking foot is a small price to pay (I know, with some machines they are pricey) if it gets you the results you want.