I have lots of opinions on your questions.
The French in particular have created many different registries for TBs and part TBs. In the past ten years or so, a new one for racing part TBs has come into existence. It’s the AQPS (Other than pure blood) and is the French equivalent of the Weatherby’s Non Thoroughbred registry which has always been available for registering part TBs in Great Britain. BUT Great Britain and France have also always allowed part breds to race in flat and steeplechase racing.
The US Jockey Club doesn’t have an equivalent registry, although it did try for a while with the original PHR. One reason for this is that part TBs are not allowed to race here at all in either flat or jumps races. This is stupid, as the European registries will eventually let superior part TBs into the main book and thus keep a tiny trickle of fresh blood into the breed there. Our Jockey Club will not do that, nor do our state racing commissions allow part TBs into TB races. (Not sure if there might not be some anti-trust implications here).
What this means is that European TBs and part TBs are allowed to prove themselves against each other, both on the flat and over jumps. The part TBs do extremely well over jumps.
In this country, the pure blood rule only dates back to the 1950s or so, which is, in a way funny, because until almost that time many US bred TBs were not considered full TBs in the UK under the Jersey Act and were therefore much less attractive to breeders regardless of their accomplishments. It might be that the US TB establishment decided to go with full TB only racing to keep exports attractive–there had been very few exports of US bred stock prior to the repeal of the Jersey Act.
At any rate the major impact was on jumps racing where part bred TBs had raced with success.
Another factor in the loss of the sport type TB was the loss of purpose bred jumps racing breeders. Very, very, very few jumps racers are purpose bred these days. They are most flat racing culls and mostly geldings. There are no NH stallions in the US. Jumps racing is so tiny, that the US can’t or won’t support a breeding industry. So the jumps racing bloodlines were allowed to die out. There are probably no living intact male descendants of the great jumps racing stallions of the 1940s and 50s–Battleship and Annapolis by Man O’War, for instance. (Parenthetically, we’ve almost let the Man O’War lines go extinct on top). And, of course, US racing is now predominately dirt sprint racing, not turf and not distance, which is another reason European TBs are not like the majority of US breds. So the US lines that featured stamina and movement that was efficient on grass weren’t and aren’t used in breeding for racing.
The other thing that has happened is that professionals in showjumping and dressage don’t want to make babies. I would assume the same is true in hunters. It’s so much easier to go to Europe and buy horses who are already well started under tack–almost show ready–as the risk of duds is greatly reduced. How many barns are left who are like Frank Chapot and Bruce Davidson who can and will breed and bring along prospects? The USET no longer owns horses.
The TB industry has changed; the American TB has changed; the sport horse industry has changed. All of these changes have led to the box those who believe that the TB could still compete at the highest level now find themselves in.
There are still a few TBs standing for sport horses. Yellow Creek and AFR, Castle Cove, Innkeeper, Fun and Fancy Free, Audited, Salute The Truth, Mystic Replica, Coconut Grove–but they are all aging fast. I love Roanoke but he too is aged. The young TB sport stallions, if there are any, are few and so far off the radar that most of us don’t even know about them. There is no sport TB marketing machine.
And yes unfortunately, we are in a box. But does the performance type thoroughbred need to be forever chained to a racing industry? It has already been stated that we do not use racing types, for that matter we do not use racing quality gaits.