Racing != Sports
Many people make the erroneous connection between sportscars and motorsports. There isn't one. Even then, FWD cars are often used for racing - from grassroots right up to top national tier racing like the BTCC. But then the BTCC uses, typically, hopped-up family sedans. They're probably the fastest FWD cars on the planet and actually used in motorsports, but they sure as eggs ain't sportscars.
A sportscar is primarily a lightweight coupe (FHC/DHC) with space only for two adults - maybe two kids too if you're lucky - with the focus on quick road driving without, necessarily, a focus on actual speed, just the preservation of it through low weight, good road holding and good driver feedback. The Lotus Elan S2 fits this description and is FWD. The Mazda MX-3 does too (and adds a sweet little V6). The Saab Sonett, the FIAT Barchetta, the Ford Puma, Toyota Paseo, Mitsubishi FTO and Alfa GTV/Spider are all FWD "sportscars" too.
All that FWD does is make the cabin space bigger.
I agree with all of this. And the FF drivetrain this stands true. The RX7 I wouldnt call it a "Touring Car" as tuned its not really "that" stable. It is a borderline but I see it as more sports car but on a larger size.
Now, with the logic you posted there (not arguing it at all just curious of your viewpoint) a Mustang, Camaro and Challenger are NOT sports cars because they are HEAVY. Really they are not when you get down to it, they are "Pony Cars" but they do fall into the "Sports Car" category at least here in the US. At least as a different class of Sports Car. Whats your view on those even though they are FR cars?
Also, a Corvette IS hands down one of the greatest American made "Sports Cars" and it too is really big and heavy. (BTW I am not a Chevy fanatic at all just pointing out the truths in US autos). I see the Corvette as a Sports Car and NOT a Supercar (at least most editions of it)... Supercars are high dollar, low production cars (this is where the standard Corvette fails) that put out dream numbers in tests on the track. Where would this car get dispositioned in your categorization?
Again, I am NOT being argumentative at all, just curious of your views on these questions. I see "Sports Car" as a coupe that handles well, has at least some get-up-and-go (relative to its class as there are MANY classes of sports cars to me), and fun to drive.... Yes they are usually 2 seaters or 2 seats with a TINY back seat (like my Mustang)
Using the logic you have a Mitsu Eclipse is a sports car (it is) but a Corvette is not.
Here is a "rough view" of how I see the market (again here in the US). This is the "selection" of cars in the dealerships.
Disposable Car (cheap hold no value - Drive it til they die)
Sedans/SUVs/Trucks/Sport Coupes (Average useable car)
Sports Cars (Pony Cars, Lightweights etc... the less practical car but fun and turns heads)
Super Cars (these USUALLY are not on the dealership lots and if they are they are showroom cars)
On topic, I think an MX5/Miata IS indeed a sports car... It is just a different class sports car than say an RX7 or a Corvette. That is one reason why they are such a hit with Autocross members. Its an inexpensive sports car that drives solid and consistent with most drivers. Its not fast really but those things hold the road for what they are and their price!