@pixeloriousspriteson Honestly, that only, really depends on why and how the reactive dog is reactive. With certain types (terriers, bullies) it can be bad or even dangerous because those breeds, by selection, have kept the entirety of the predatory sequence, whereas in other breeds it's usually one or a few segments that were selected and encouraged depending on the breed's purpose and job.
There are many common games and sports that can be bad for a dog's body because many dogs are not 'functional' ie selection took only looks into account as opposed to how emphasizing certain traits would influence the dog's mobility and general health. Hence why you'll see that certain larger breeds won't sit 'properly' or go down in sphinx position if they can help it. People love heeling and love making their poor dog look at them the entire time but that's not good for the dog, or at least, it's particularly strenuous on certain dogs.
However, how many times a day and how long would a healthy dog with no joint issues have to play fetch to get issues from just that? It is recommendable though to throw the toy so that it won't make the dog execute... risky maneuvers for their back or legs, like throwing it behind them while they're already rushing towards you.
Destroying toys is perfectly healthy for a dog, as it satisfies a natural instinct much like picking up and carrying a stick or, yes, fetching.
If your reactive dog doesn't choose to chase after the trigger (ex, a dog that's triggered by children or small dogs and wants to catch them) I would say don't worry and keep playing!