You seemingly have no idea how powerful a 20 gauge shotshell is, how successful it has been as a sporting round for decade after decade. Recoil? We are talking about one blast against a human threat, not a sporting endeavor. Your quoting of a marketing angle, and Wiki, no less...
Birds? Size? The 20K+ makers of shotguns (Benelli, Pioiti, etc) sell plenty in 28 gauge. You match the size to the game...the size, weight, fit, maneuverability, the ease of raising to battery and targeting of the shotgun to match the task at hand.
Home defense "capability"?
There isn't a pistol, or very few rifle cartridges, that can stop an intruding human threat as effectively as the energetic blast of the most mundane of .410 shotshell loads...
Few survive being plugged by any shotgun.