Endurance ride nutrition

Reviving this thread to ask a similar question:

Lately, the podcast has really been big on pushing ‘fueling the ride,’ and that’s certainly something I agree with and have had good experiences with.
I recently did a long ride (Town Hall? Alleghany? Some other one?) and the workout text was specifically discussing how on these long endurance rides, it’s beneficial to not take in carbs/sugar, and let the body use fat, and that if you were intaking sugar, you’d blunt that adaptation.

So now I’m a little confused. I understand carb intake and I understand the core concepts of fat adaptation, so I’m more specifically curious what that workout text was trying to convey with regards to bike nutrition in general. I sure couldn’t get through 3:15 or 4hrs without supplemental intake, unless I ate a truly monstrous morning meal[s], and even then I don’t know.