I've never used them, so it's not a bee in the bonnet thing. I just think it's a shame that there are so many posts, like this one, asking should they alter plans, make an entire trip, etc...around these "crowd" calendars. I have read the page you hyperlinked (I like TP for the crowd sourced wait times only, but have read the rest of their website). In reality, they aren't even trying to predict crowd size. They're trying to predict ride wait times, which may or may not have anything to do with actual crowd size. So why call it a "crowd" calendar, when that's not even what they're actually predicting? Deceptive and misleading name, IMO. They are trying to make these predictions largely on years of historical data. However, WDW is ever changing, so what happened on a random Tuesday in August 2016 may have nothing to do with what happens on a Tuesday in August 2019, as things have changed. There are variables that simply can't be accounted for. The biggest ones of course are weather and attractions going down. When that happens, it can have huge impacts on ride wait times and actual crowd size. As has also been said here, even WDW doesn't know how many locals, APs, etc..will show up on a given day. A 1-10 scale is really subjective anyway. You may walk in and say "wow, this feels like a 9" and someone else will walk in and say "Gee, not too crowded today, I'd say it's a 5".
There's a reason various crowd calendars are in complete contradiction to one another so often...they're just wild guesses. IMO, they're snake oil.