Oh it definitely is. Having stuck an XTR on the back of my road bike I’m enjoying the silence and not mourning the couple of watts loss in efficiency (or the lack of front derailleur…)
Some of the roads down this way are questionable mind.
It's not like chain slap is a thing on the road whereas speed generally is
Because brands have realised that cramming more gimmicks into stuff sells, gone are the days of minimalistic and lightweight. And gravel too, everything is a gravel bike now.
And then there's a clutch in the derailleur, and that adds a good chunk. I'd expect Shimano adding clutches to road derailleurs next generation.