I have always tailored my ignition timing on 1960’s and 1970’s cars to my driving style. Changing the base timing for better throttle response is simple, as a teenager I would do this without negative side affects.
For a common street car when the mechanical advance springs are changed to allow full mechanical advance at 2500-3000 RPMs there is a significant power increase.
For a 5000 lbs truck with a small engine I would just advance the timing by 5 degrees from stock and monitor for spark knock.
I had a 1962 Chevrolet C10, I set the base timing to 10 BTC, it would knock at low elevations like Death Valley but perform reasonable otherwise.
Some people, me included, can’t leave stuff the way the factory decided it should be. The factory’s priorities might not be the same as mine. Being a research and development engineer, I experimented with this stuff for a living. Part of the reason I can’t leave any of my cars alone. My Mustang has lots of parts that are not factory and it is better, in my opinion, for it.
No disrespect to the statement or anybody that agrees with it, just a different opinion.
For decades the Ford V-8s were notorious for wearing out timing chains and as they wore ignition timing would retard. The average DIYer didn’t have a timing light but found that moving the timing ahead slightly made a significant improvement in performance and economy so they bumped the distributor ahead every time they did a tune up until the chain was replaced and suddently they find that the starter won’t crank the engine.