Is it reductive when its describing a group of people that like something and refusing to hear any ill of it? The comment wasn't shade at people using the language in general.

And you're right, fanboys are in every language. But resorting to changing the argument by whataboutism is a bit reductive.

I’m not a go fanboy, but I do know from other contexts that so-called “fanboy“ behaviour is frequently associated with level-headed supporters getting defensive in the face of imprecise criticism.

There’s an oft-repeated pattern where valid specific criticisms morph into broad criticism, which morphs into judgement, which breeds defensiveness, which feeds the criticism. Once you recognise this pattern, you see it everywhere.