The responsibility of the devs is to deliver what was asked. They can and probably do make notes of the results. So does QA. So do the other stakeholders. On their respective teams they get the same BS from everyone who isn't pleased with the outcome.
Ultimately things are on a deadline and the devs must meet requirements where the priority is not performance. It says nothing about their ability to write performant code. It says nothing about whether that performant code is even possible in a browser while meeting the approval of the dozens of people with their own agendas. It says everything about where you work.
We always have discussions here about how you have to learn to talk to communicate your value to clients in a language they understand. Same goes for internal communications.
Software development isn't factory work. And factory workers are expected to notice problems and escalate them.
Anyway, they're paying me far too much to have me turn off my brain and just check the boxes they want checked in all situations. Sometimes, checking boxes because they need to be checked is the thing to do, but usually it's not.
We're definitely way past the point where there is a singular definition of what "software development" is supposed to mean.
I also didn't describe anything like factory work.