You completely missed the point GP was making. Yes, sugar is an easy fuel source. The point is we have NOT evolved to consume massive amounts every day without breaks (i.e. daily) and without lots of fiber to buffer it.
I think you might be the one that’s missing the point. I’m saying some sugar is absolutely fine as part of a balanced diet, this isn’t a controversial point. Excessive calories are bad, whether they’re sugar or anything else.