Quick question - have you visited both parks in the last 1-2 years and can compare the actual character interactions on a typical visit?
You literally can’t walk through town square without seeing characters unless you arrive during the flag retreat or right before a parade. I definitely remember things being similar at MK prior to Covid - although with less hours.
Sure, although more times at WDW than DL.
Can you see some characters walking around, DL sure. But we aren't hanging around town square/main street all that much, as we are walking around actually going on rides across the park. Second, at no time did I see a line of people waiting to interact with the characters walking around the park, of the same length as i saw for Ariel, or Tinkerbell, or Mickey and Minnie at the M&G's at WDW.
I also didn't see (and granted we were never in one spot for long enough to actually measure this accurately) the characters staying around and interacting with guests for hours on end, like they do at the WDW M&G locations.
So yes, could one person at DL decide to spend their day just walking around, interacting with every walking character they see? Sure, and if they did that, then yes that one person is likely to see more characters and a greater variety of them than someone at WDW. But what is the percentage of the customer base at WDW that is willing/wants to spend their day just wandering around the park for those interactions? And even then you're hoping you will be in the right place, at the right time, to hit the characters you want to see. Whereas in the WDW M&G model you know exactly where the characters you want to meet will be. You know the times they will be there. Heck i believe back in the day you could make FP reservations for some of the character M&G (we didn't look to do them the last 3 times we went to WDW so i don't know if you can book them with Genie+.
WDW's general model, but especially as it pertains to M&G's isn't about trying to maximize the amount and variety of characters any one individual can meet and interact with. Its about trying to set up a method so that the most people, get to see the most popular characters, in as reliable way as possible.