I’d guess it’s because pros pushing their 53-39 cogs are fine.
As for me on my 50-34 11-32 combo (a ratio that with 3.5W/kg is perfect) I tend to find the gap is a bit too much (though I’m getting used to throwing the right hand brifter two gears to compensate). In comparison to my 50-39-30 triple I tend to find the triple gives me more comfortable cadences more often (3x8 vs 2x11) but I guess half of that is not wanting to hammer around both sets of cogs so often.