If you want to get into details, an apartment that's only one room is a Studio. I understand that there's a difference between my Studio and the ones you mention. Professional and Amateur. Mine would be the latter, but it's still a Studio nonetheless.
The same way Andy Sneap is a way, way, way, way (+100 ways) better Audio Engineer than I am, we still are both Audio Engineers nonetheless. Just because someone has more (experience or gear) than someone else, doesn't give them the right to revoke the title from those with less.
I, and many others, have spent years learning and struggling to make ourselves better at this, and for you or anyone else to say that we don't even do it at all is disrespectful.
We spoke about recording studio, don't go the apartment way please
Dave Pensado and Dylan Dresdow have really awesome place at home... Both call thoose project studio not studio.
Once again you can compare a multi million facility like Larrabee to a home studio/project studio. This is not the same thing so why use the same therm?
And this is have nothing to do with who you are (Grammy winning engineer or almost unknown).
I don't question your skill or the fact you are/aren't an AE.
For me you are an AE when you are paid for doing it. Period.
In a certain way I agree with you Mickaël-Ange about using the term "studio". A home-studio is definitely not a pro recording studio. Period. But I also see it as a generic term to describe a place where some music is recorded and produced. Easier to present yourself here and there even if we talk about someone with only a few years of experience working in a small place with just a few recording gears and plugins (although the term "home-studio" is very understandable too ahah!) Yeah semantic is important...
In other hand, if a "real" "pro" studio means everything you said (acoustic treatment, etc.), Tue Madsen's Antfarm for example is not a studio?? I mean this guy works at home and his facility doesn't look like the golden studios you mentioned but he delivers top notch productions! So what word could fit in that case?
I also see a guy working in a really good studio with tons of great gears (because he's got tons of money!) and the result was just horrible.
My problem (and it's the same for many other people) is that today, most young artist and musician don't know the difference between both.
A guy with a mbox in his bedroom have a studio in popular word.
Same thing for many A&R, label executive...etc
Antfarm is a project studio.
For your last point, don't blame the tool instead of blaming the guy behind
You can have a really fast car and doing a race again Michael Schumacher driving a clio. He will still make you cry like a baby at the end.
Andy Sneap mix still sound like an Andy Sneap mix no matter what he have for do the job.
You can do terrible mix working at home studio, project studio or studio like Record Plant.
It's the guy behind, not the tool...