I don't think I've run into someone that thinks the NEP was authentically Socialist, but the collectivized, publicly owned and planned economy that defined the Soviet Union for the majority of its existence as "counter-revolutionary." The NEP had more literal bourgeoisie and was defined by controlled markets, it's still a form of Socialism but it's common to deny it that along that basis. Are you a Bukharinist? Do those even exist? Even then, Bukharin seemed to just want to lengthen the NEP, not perpetuate it forever.

Genuinely, this is a take I haven't seen spelled out before. I don't agree, of course, but I'm curious what your reasoning is.