Sure, by all means, let's listen to the brothers of TJ Watt. It's not like they have any skin in the game??
Seriously though, comparing a DT and DE with basic stats and zero context is not the way to analyze the impact each player had or the situations they faced.
Like you said, AD is basically facing a double-team every snap with a triple team sprinkled in.
TJ Watt is a great player, but he gets to operate in a lot of space on the edge.
To be fair, maybe Watt did face a lot of double teams or chip blocks? He probably did, but I don't watch many Steelers games.