>>1502627>ranget.leglet 500% gear range is more than enough.
>ease of shift1x shifts faster and easier.
>less gears on the back so wider more durable chains and cogsGo for wide range 9 speed if that's what you want, box prime 9 or something similar.
>easier dropout alignmentThis has nothing to do with a front derailleur, shit dropouts are shit, don't buy a bike with them.
>easier gear adjustmentAdjusting 1 derailleur vs 2.
>less weight on the rear hubYour one good point. Unsprung weight is most definitely a problem with the dinner plate cassettes people are running although I'd argue that a 3x or 2x system doesn't fully mitigate this though and other drivetrain systems like gearboxes or gearbox hubs should be considered to properly mitigate this.
>not running out of speed on the downhillYou aren't running out of gears on the downhill. Let's go with a conservative gearing estimate: 11,32 on 27.5" tops out at around 40km/h. If you're reaching that on a course with anything remotely interesting on it you'll be doing it on a dh bike or an enduro bike getting close to dh bike territory. On both bikes you'd just use a larger front chainring to avoid running out of gears.
In other cases not covered by the above see: "inb4 gravel bikes and other glorified road bikes"
>cheaper mehcanically more robust componentsCost: 2x and 3x groupsets with valid comparisons i.e 2x Xt 11sp and 1x Xt 11sp show the 2x/3x groupset costing more.
Robust: wide range 9 speed.
>overall mechanical advantage and SIMPLICITYEngineering is the art of tradeoffs; for what you gain in gearing advantage in a 2x or 3x system you trade for chain security. Do you really need more range than a wide range 1x system offers? I'd say no. Do you need chain security? I'd say yes.
>MUH SIMPLICITY1x and 2x/3x are pretty comparable in terms of simplicity, yes 1x needs tighter tolerances but it only has 1 shifting mechanism. Picking a bad design simply due to simplicity is a stupid idea, balance is needed.
