Depends on how good the implementation of a given protocol is for a product. Just because it has an RJ45 jack (look that up), doesn’t mean the circuits behind it are robust.
While I know what an RJ45 jack is, I'm not sure how that or the rest of what you wrote above relates to your statement that a cable that is designed to pass signal better than a lesser cable actually performs worse in a circuit designed for the lesser cable.
Just look at the brouhaha over the ESD issues the X32 had.
People who used cables other than that specified sometimes had issues. Not ok for pro work.
The issues were from people using exactly the cable that Behringer specified at the time, which was unshielded CAT5e, with Ethercon not necessary. The quote in the Behringer literature, which you can't find anymore, was something like "any CAT 5e cable that can be found in any hardware or other store".