I'm not sure exactly what you mean by a "worm tunnel", but it is well known that rust often forms in scratches, and on rough surfaces. It's one of the reasons that people say that when you get a surface scratch on a car, you should sand it down to bare metal, apply a primer to the area, then paint, and then only add the usual clear coat, rather than just re-applying more clear coat alone. Obviously the sand/primer/paint/clear coat routine doesn't apply to skates, but it might be another possible reason to justify trying to maintain the very smooth finish you work so hard af, even to the sides of the blade.
I could speculate that there is simply more surface area in such areas to react with oxygen, and/or that the electrical-chemical forces are larger (just like sharp objects attract lightning, because electrical charges can be shown to tend to move towards sharp points and towards high and low points - something explained in 1st year college physics), and/or that for some reason valence electrons are more free to react when there are no atoms to share electrons with in more than one direction, but I really don't know. I presume the matter has been studied in some detail by appropriate experts.
In any event, if you did form a scratch, it is completely reasonable that moisture and oxygen would sit in the scratch for longer without evaporating than on the outer surface, and that corrosion could develop around there.
A lot of rink guards and coaches are constantly going on and coming off the ice, and have to walk for some distance before they can adequately care for the blades, and don't have time to do a thorough job of drying the blades first. When I played rink guard/rental desk person I personally did use hard guards going back and forth between the two, because soakers wore out too fast, but I used paper towels (applied twice) when I could, and I used stainless steel blades. Plus, once I take off my skates, I don't use guards at all, but let them air dry after drying them with paper towels, and sometimes oiling. Of course that won't work for someone who puts their skates in a bag in the middle of things that might abrade it - they may need soakers to avoid abrasion.
I recently bought a (used) hockey bag. Part of the outside skin is nothing but a rugged mesh. Way better, IMO than the expensive figure skating bags that look like suitcases, but have no ventilation. (It is, however, larger than is needed for my figure skating stuff.) Many figure skaters would hate the idea of buying hockey related gear, but some of it is good quality, and is much more durable than cheap supermarket bags.