Ideological what, now? Bicycles, you may have noticed, are muscle-powered. adding a few dozen pounds' worth of wheels and frame is going to seriously impact acceleration, hill-climbing, and rider endurance, and the increased width will have major effects on hazard avoidance, navigation in narrow spaces, turning radius, and general maneuverability.
I've ridden adult-sized trikes, and they are fun and relaxing, but they're much less suitable for most serious transport/travel applications.
If you want stability above all else, sure; tricycles exist and are more stable than bicycles, and you can go up to 4 wheels, too. They have other downsides, however. More friction, more width needed to both travel and park, and actually worse stability when cornering at speed (they can't lean, so are at risk of flipping in a turn).
Cargo bikes often have more than two wheels, but people who don't need to carry significant weight in a basket tend to prefer bicycles as the more practical option. Parents in Copenhagen do often choose the tricycle-with-basket at a moderate speed, as a safer option than putting a kid on the back of a bicycle. But that only works when you have wide bicycle lanes.
..or, absent ideological zeal, the number of wheels.