Would a standard luminosity (max. 200 cd) HDR TV make sense?

Answers to this question say that HDR TVs are capable of displaying a "higher bit depth", a "wider gamut".

However, I see that most (all ?) HDR TVs are also capable of displaying high brightness (1000 cd+).

Is it a necessity for the viewer to see the benefits of HDR ?

Would a "higher bit depth" / "wider gamut" be perceivable by the human eye if HDR TVs where only as luminous as standard HD TVs ?