I'll upshift to 4 5 6 without a clutch "sometimes" The only bent shift fork commonly heard from is 2nd gear, And I'll make an educated guess that has more to do with clutched heavy power upshifts and the larger spread there due to neutral, than no clutch shifting. Pretty much every part of riding a motorcycle is an acquired skill. Plenty of ham hand guys have ruined trannies while using the clutch. We box stock sprint and endurance road raced a 1982 CB900F for 25,000 miles then I sold it, to a "hot rod" street rider, it was last seen at over 50,000 miles with the engine/trans still untouched. Shifting and running just fine. Mo-sickles are pretty tough these days. Only motorcycle trans that failed on my watch was a Norton that some SOB speed shifted on a "for sale test ride" A quiet rural evening, I heard the fatal shift in the distance. He snapped the input shaft on me. Wasn't till the next day that I suspected the damage. That big ol' clutch hangs WAY out there on a shaft in a shaft bearing on the Nortons. No other damage, just had to replace the shaft and as a precaution it's support bearing. Not bragging but I can clutchless shift smooth enough that the passenger doesn't know the shift happened.
And yes I have driven many a box with a no synchro first/reverse and my fair share of completely non synchro all double clutch forklift and tractor boxes. Usually decades after they left the factory with shifters so worn and sloppy that engaging two gears at once is possible. I still use a FarmAll H that's like that. And yes I can double clutch and shift it while it's moving. ( there's a lot going on at once to do THAT.) IMO more tranny damage has been done by slow indecisive shifting than by "know what they are doing" get r done shifts. Who hasn't heard a newby tentatively trying to coax a tranny into a gear just at the point of mesh and you can hear the dogs rattling against the slots "slowing down" the speed mismatch. No tranny will take THAT treatment for long. On motorcycles the newby's; pull the clutch, release all throttle, wait, THEN tentatively slowly lift the shift lever towards the next gear can really make a dog rattling ear cringing racket.