If it's too generic I can imagine it'd be difficult to preclude DoS attacks aren't possible. I guess we'd have to be suspicious of operations where the computational cost isn't proportional to the operation's size, but I don't know enough about bitcoin script to imagine OP_CAT breaking that.

The referenced article: https://medium.com/blockstream/cat-and-schnorr-tricks-i-faf1b59bd298

Yeah basically. It was originally removed because of a now patched denial of service vector, but you can do eltoo, covenents, and kinds of stuff with just op_cat. Even the block stream article I was reading about op_cat schnorr tricks said it needed deeper review due to what its capable of.

I like the check template verify (CTV) style of BIP better