Just reading older posts to catch up and knowing this is @MadScientist thread the following had me thinking and then looking at some of your topics and posts Rick an may have an insight for you.
One can grow good plants no matter the size of the pot. The plant size is relative to the size of the root zone - smaller rootzone, smaller plant, bigger rootzone, bigger plant. But yes they are a pain to re pot from a fabric pot but that's why you don't, or do it early in comparison.
True its hard to over water them once there established, but drying out in a day well that depends . If running a perlite/coco mix yes the turn over time between watering is a lot less than say straight coco.
True and it does happen especially in the early stages of growth, which over time as a plant grows it will need more frequent watering anyways due to the respiration of a bigger plant.
But the salt build ups, lockouts and pH issues, are usually caused by other factors. not entirely the plant being big for the root space but it just augments it. A plant is to big for the root space if the medium can't hold enough water between watering's where that is hrs or days or weeks. So in order to buffer that growers tend to go to bigger containers or to mediums that have more water holding capacity, thus keeping the same watering duration which is obvious.
Salt buildups like any media occur when the plants aren't utilizing all the nutrients fed to them but you know this. The leftovers become saturated in the medium leading to build ups, so as you know one has to either feed at a lower concentration, flush periodically, or consistently have run off to keep that build up at bay. But sometimes buildup occurs due to evaporation of the water from the media before the plant has time to utilize all the nutrients.
As for lockouts they happen either due to pH going out of acceptable range, or from nutrient concentrations going to high causing the plant to lock itself out. The pH naturally drifts slightly more acidic over time as the plant flowers, and if not taken into consideration can lead to lockouts further into flower if things go bad and build up is present. pH also changes due to external factors, such as bacteria or algae growth, which can cause that change by its own growth.
The other lockout situation is when plants are run too dry and start to loose that "static pressure" or as we say the plant drupes. In that situation if the plant is fed at a "normal" nutrient rate. That plant is so thirsty that it doesn't care that its also taking in all the nutrients present as well. So instead of being selective through normal cation exchange, the plant burns and then proceeds to lock itself out from taking up more nutrient laden water, preventing more damage. Solution is to feed just straight water or lower feed water till the plant builds up pressure and normal operation again then resume with normal feed.
Now if running media's or mixes that drain quickly and don't hold as much water such as coco/perlite mixes vs straight coco and also running higher feed rates, lockouts, buildup's and others issue's can occur pretty quickly. But as you noticed you just have to feed at lesser feed rates, and water more often with runoff to counter act that.
Personally i run straight coco now as its holding capacity for water is greater allowing me to water less frequently than when i was running with perlite mixed in, but its easier to over water initially in straight coco. Also i typically can only feed up to around 1.2-1.4ec of my current feed before running into buildup issues, but every nutrient is different as if i tried to run a 1.2ec with some nutrients ive tried in the past they would just fry my plants in a hurry due to higher nutrient levels that corresponded to ec readings. Example i was running +2x actual molar concentration of nutrients at the same 1.2ec.
Anyways long winded thought or insight to consider.