+1
For me it's not a strict must, but it's extremely convenient for me to salmon on a sidewalk for about 300m to make a left turn into a driveway where the road has a hard curb median, so I can't (easily/safely) get across right there.

Also coming out of my townhome complex, riding 'downtown' for errands is a left turn, so I take the sidewalk until I get to the intersection with the light where I cross.

The key is, I consider the sidewalk not to be my home; I ride slowly and courteously. Always leaving oncoming pedestrians plenty of room; never buzzing pedestrians going my way; if they have headphones on and don't hear me, I keep my distance and just roll at their speed, so if they do notice me they don't think I'm trying to get past them (because I'm not). Maybe if it's a long time I'll look for an opportunity to hop off the curb and salmon in the bike lane for a few seconds.

But this being SoCal, there are hardly any pedestrians anyways, so I only ride on sidewalks because they are underused public resources. If there were lots of pedestrians, I probably would not ride on the sidewalk.