The attitude to theoretical computer science re quantum is really weird. Some people act as if "I can't run it now therefore it's garbage" which is just such a nonsense approach to any kind of theoretical work.

Turing wrote his seminal paper in 1936, over 10 years before we invented transistors. Most of CS theory was developed way before computers were proliferated. A lot of research into ML was done way before we had enough data and computational power to actually run e.g. neural networks.

Theoretical CS doesn't need to be recent, it doesn't need to run, and it's not shackled to the current engineering state of the art, and all of that is good and by design. Let the theoreticians write their fucking theorems. No one writing a theoretical paper makes any kinds of promises that the described algorithm will EVER be run on anything. Quantum complexity theory, for example was developed in the nineties, there was NO quantum computer then, no one was even envisioning a quantum computation happening in physical reality. Shor's algorithm was devised BEFORE THAT, before we even had the necessary tools to describe its complexity.

I find the line of argumentation "this is worthless because we don't know a quantum computer is engineeringly feasible"

1. Insulting,
2. Stupid,
3. Lacking whimsy,
4. Unscientific at its core.