starting fluid, very detrimental?

As stated starting fluid can do damage. Have you ever heard how the engine knocks/bangs/rattles? That is like running 87 octane in a 12-1 engine at 1500 rpm and 50 degrees advance floor boarded. That said, there is no reason it can't be used in moderation. Just a little squirt, crank, start, stall. repeat.
You really want to see damage? Take the oxyacetylene torch, stick it down the carb, turn on the acetylene, and the oxygen but don't lite the torch. Then hit the starter. Crankcase full of explosive mixture, and we have ignition. The engine started but all the oil came out from every displaced gasket/seal.
Did that about 60 years ago when I was a little dumber than I am now.