You have a point. However, I just wanted to say that pros have thought about the pros and cons of 1x vs. 2x much more than we have, and for them marginal gains are much more important.
That’s totally fair. Like I said, I prefer SRAM’s line-up, because it gives the 1x and 2x community pretty much equivalent options with an easy to understand compatibility matrix. Shimano’s is a mess and gives cyclists many fewer options. If you prefer 2x, you have plenty of options. E. g. in addition to the 10–33 cassette (which has the same range as Shimano’s 11-36 cassette), you can get cassettes with more or less range if you wish. SRAM has 4 cassettes that are compatible with its WIDE rear derailleur, plus 3 more that are 1x only (10–44, 10–50 and 10–52).
It is clear that Shimano’s road and gravel groupsets are designed by different teams that don’t seem to be talking too much to each other. It seems that they want to make it difficult for people to mix and match components. I know roadies who prefer the shape of GRX levers, but currently can’t put them on their 12-speed road bikes. (I reckon, living in Shimano land, that the road groupset team has the most prestige inside Shimano, a distant second is its MTB groupset and then comes gravel. I mean, how many years has it been since Shimano has released 12-speed MTB drive trains and we still don’t have 12-speed Di2 mountain bike groupsets!?!) If I were Shimano, I’d release way more chainring options than just 40 and 42 teeth for their 1x crank, for example. SRAM offers 38–54 (or 56?) in 2-tooth increments.
I don’t find that very convincing. Plus, I don’t think this is true in practice: the biggest bit of aero drag is the sack of water we call our bodies. I am pretty sure I am more aero on the bike that allows me to spend more time in an aero position, not whether the hoods by themselves are more or less aero.
I am much more comfortable in the aero hoods position on my SRAM-equipped bike than on my previous Shimano-based bike. My Shimano levers had fatter, but less tall knobs, so a road imperfection could knock me out of my aero position. Newer Shimano groupsets are better, and perhaps GRX is better still, but I very much like the size and shape of SRAM hoods. (It isn’t the bike fit, I have had quality bike fits, and the fits of my old and new bike are equally good, modulo differences in geometry.)
I’m not saying you have to share my preferences, my point is simply that ergonomics matters when picking a groupset.
Regarding aero gains of 1x, I don’t think I mentioned the absence of the FD as an aero benefit. If there is an aero benefit, I reckon it is quite small because the air in that region must be super turbulent from those stupid legs that keep on circling around in that region 
I think the biggest gain is that the lack of a FD gives frame designers more freedom and allows for more tire clearance.
Plus, a lot of riders don’t like shifting chainrings. Most roadies I ride with (and myself included when I was on 2x), we’d stay in the big chainring as much as possible, and the chain line must have been less efficient as the chain angle is more extreme. That’s why I kept my 11–32 cassette and opted against a 11–28 cassette: on the latter I didn’t want to use the 50:28 gear combo whereas with the larger cassette, I could and did get away with it. That was quite useful to get over some short kickers, bridges and climbs.
