I think it depends on what you mean by 'purist'. if by 'pursit' you mean an artist who only trains to fight against people attacking them in like manner..well that only really happes in sport competition anyway so it's kinda an even thing. I mean, a striking purist will not train against shoots and a grappling purist will not traing against kicks to the face so... I saw some Judo matches last weekend and they had some really nice takedowns but none of them were trying to punch or kick
If by 'purist' you mean 'one who only trains in there art, but trains for general s-d/combat', then I think *anyone* if going to train their art against any kind of attack. A TKDist will train to use defenseive footwork and hand stikes against a shoot. A grappler will train to use traps, and evasions etc...against kicks and punches.
There's a difference between training in another art and training to use your art effectivevly against a full range of attacks. For example, the move I saw in the match, the defense against the double-leg attempt, the arm and shoulder motion of the left arm of the defender was the same motion as a palm heel block. The more I leatn TKD as a defense art, the more I realize how many of the basic arm and body motions can carry over into a wide range of attacks.
I mean, in both matches I watched lst night, the attackers trying to shoot in must've *really* sucked because the defenders who were trying to keep the fight on the feet were pretty good at not allowing the takedown to work (if it's your contention that a well trained striker cannot hold against even mediocre takedown skills). The one time that that shoot seemed to actually go to the ground is when the defender used his defensive motion to spin the attacker over and the attacker went down on his back and started to get abused from above. I have a feeling it's because the guys who defended and stayed up striking simply trained to do so; and in the end, the better training, the better execution, won out. Not superior techniques but superiour execution of techniques.
A smart striker will train to defend against a grappler's takedown, if he is traiining for street defense. A smart grappler will train to defend against a striker's attack, in like manner. A striker who does not train against takedowns is either optimistic, naive, or only doing it for sport within his own art.
In other words, I disagree with your contention that "a grappler trains to get people down...a striker doesn't train to prevent takedowns". To be successful in life, in self-defense, a striker had *better* train to prevent takedowns, and in the end, it's the training and execution that will prove out