I don't disagree really. I do think there are in-this-context significant differences between how individual saints are interacted with. A personal or family patron saint tends much more towards looking like ancestor veneration, compared to eg mary who in practice takes a role that would in other religions be filled by a deity of femininity/motherhood/nurturing/etc.
But overall in any case I think it's sometimes valuable to think of christianity this way and sometimes not. It is a syncretic religion so of course it has regional variations and contradictory remnants of absorbed practices. IIRC some of the specific saint traditions, like icons in the home, predate christianity in the mediterranean.
But on the other hand there are practices and relationships common in true polytheistic religions that you don't see in christianity at all. If taking the saints as minor deities, you don't find sects exalting one of them exclusively, nor do you see individual christians "defect" from one saint to another for personal advantage. There's no theology of competition or opposition between the saints to base such practices on at all. So there are limits to the usefulness of this perspective too.
The shintoism example is interesting, I'll need to look more into it. I had considered it polytheistic but now that I think about it I haven't read shinto writings on the subject so I don't know if most shinto practitioners experience it that way. Outside perspectives aren't completely invalid of course but they aren't as interesting to me as how believers experience their own religions.