Oofta
Legend
You cannot make a platypus by "genetic tinkering". That's not how genetics works. That's the issue, really - so many people want to apply "science" to D&D without actually understanding the science. Causing those of us who actually have science backgrounds to throw up our hands in dismay.
I see no reason we couldn't build platypus. Obviously it wouldn't be "toss DNA of a duck and a muskrat into a blender". But it is how evolution works, by "tinkering" with DNA. It's how we have a chicken that's descended from long extinct therapods like T-Rex. We don't have the technology or understanding of how DNA works but there's nothing stopping us from building a very good copy of a T-Rex (apologies to Jurassic Park but DNA doesn't last millions of years even in amber) if we had better understanding.
There's nothing stopping someone with advanced enough technology from building something very much like an owlbear. Dragons, giants, oversized arthropods and whatnot obviously require some inherent magic. Owlbears? Owlbears are just animals about the size of a large bear.
P.S. Nice appeal to authority while being insulting by declaration that you know better and that anyone who disagrees with you is ignorant.