Yes, all very true, but all of that is utterly irrelevant for the home NAS in 95% of cases since performance is not that critical and it comes at an enormous cost of wasted space, also physical space is a huge deal since adding two redundancy drives for each raidz2 quickly adds up. As well as noise etc.

And if we want to talk optimized setups it really isn't recommended to add new vdevs to a already populated pool since the usage will be quite unbalanced and affect performance as well.