there are more viable options then people think.
in doubles you can switch to Zelda if u get hit up in the air and your partner dies. that way you can up b straight up and by the time you come back down to the stage, your partner will have re spawned and can protect your landing.
the air mobility is great so recovering on FD or dreamland then switching to sheik is very viable.
https://www.youtube.com/watch?v=jjxtvlwM_38#t=3m50s
obviously Zelda kills puff at 60 on any stage besides dreamland, so its no that bad a matchup. let alone punishing rest.
the Samus one is also good.
against icy's, if it is only sopo and I I am at very low % I play zelda because i dont want to take 80% off one grab from sopo since the chain grab is still amazing from icy's. if i have the lead then i don't need to risk getting chain grabbed by sopo. Usually i will only do this vs better players then me, since i'm confident in my sheik against players at my skill level or lower.
Also Zelda is great in some match ups for timing people out if its a super close set. Icy's and peach and some low tiers.
Zelda also has an infinite ledge stall that does damage. if you need time to slow down the pace and think about the match.
there are lots of situations. maybe not optimal ones. but that's how the meta is pushed. people trying new things. And i think the smash community is really bad in terms of just dismissing ideas because the collective opinion is that it is a bad idea.