In general, people have really weird notions of single bevel use. Maybe from the myriad youtube videos of people who were never properly trained? Here are some of my basic examples:
- "usuba is only for in-hand work" - I actually think of all the single bevels, usuba sees more board work. Certainly not to the same level or in the same style as a gyuto... but usuba are used for way more than just daikon katsuramuki.
- "deba being used as a cleaver" - I hate this one the most. The only people who use a deba like a cleaver are people who have never been trained in how to use a deba. If you need to cleave, buy a cleaver. Deba is a slicing knife. When you need to cut thick spines, there are gaps in the spinal discs that trained fish butchers know how cut through without using any force. There's absolutely no need to use a heavy chop to go through a spine. There's no problem using it to go through softer rib bones (though even that isn't always necessary). Even slicing fish heads is no problem with good technique. The geometry and weight are ideal for bulk processing - hence the shape. Just cuz it has a thick spine doesn't mean it's meant to be a heavy handed chopper.
- "kiritsuke is a combination of yanagiba and usuba and while it can do both jobs it excels at neither of them" - actually this one is true.

I just wish there weren't so much confusion between the single bevel and double bevel versions. They're two totally different knives and I wish they had different names.
That being said... I'm also a firm believer in doing what works for you. So if anyone likes using their yanagiba to butcher fish or just thinks a single bevel gyuto is really cool and wants one, more power to them.