I love it when folks kick the goads, or otherwise challenge all of the "they say" facts. If something makes sense, then sure, do it that way. But often, I'm left scratching my head, thinking... "I can't see the logic behind that, or can't see why that should matter!" Then, it's time to challenge it... or even dust off some of those old wives tales, and put them to the test. (Egg shape experiment, anyone???) An other one that I bought "hook line and sinker" was that young birds needed to be kept out of the flock until they were full sized, roughly 12 weeks old, so that they could defend themselves against the older birds. I'm finding, as have a lot of other people, that it's better to integrate when the babies are much younger, as they will enter the pecking order before they are perceived as a threat to that pecking order.
WAY TOO MANY black & white proclamations are made on this forum and all over the Internet in regards to poultry...
Sure some have basis in logic, study or established rules or procedures but that still doesn't equate to them being the only way to do it and the other ways 100% wrong...
Sometimes
argumentum ad verecundiam has to be taken with a big grain of salt, unless it's been repeatably proven with controlled study to be as harmful as claimed...
I do a plethora of 'wrong' things or things against convention as I doubt or challenge the conventions, and I have seen little to no detrimental effects in doing so...
Lockdown? Skip that...
Staggered hatching dates in the same incubator, sure...
Don't concern myself with humidity in incubator...
Candle every day 1 - 21, sure...
Only 10% 'treats', LOL my birds get about 5-10 times by weight more fresh foods vs commercial feed a week...
And being the ultimate rebel, I also heat my coop
Back to the OP, people have had decent luck hatching 'fertile' commercial store bought eggs, and we know they most certainly were not optimally treated for hatching purposes...
I have not doubt that doing certain things and procedures is likely to produce decent results, but that doesn't mean it's the only way to get good results...