At the same time, most 3 stock arguments are all based on feeling rather than logic:
I see that statement to be both blanket and absolutist (making arguments on 3 stock out to be simply rhetoric & not logical; absolutist due to the use of "all"). To change your opinion I will offer logical demonstration of why 3 stocks could be (logically) used over 2 stocks.
Truths are derived from axioms, for us we have competitive principles.
A principle, when rulecrafting, is Software Authority - this principle states that, by default, rules for competition start the game design provides as default (yes, we would start with Items ON and Time as the rule of play instead of Stock, however this principle does not state that these rules cannot be changed, simply that it is the starting point).
Competitive Value is a principle that allows default rules to be changed if there is more value for the change of rules. Obviously it has been decided that Stock is more valuable than Time and that Items set to OFF provides more value than ON, as well as various other rules like Team Attack, etc.
By default we start with 3 stocks as determined by the software.
Therefore we would have all the reason to try out 3 stocks first to weigh the value versus 2 stocks (which has been and is currently being used).
There's actually MORE reason to use 3 stocks than 2 at this point. We know 2 works. People are ok with it.
We know people want 3 stocks.
We do not have enough practical use of 3 stocks to determine which is better.
We don't need anymore 2 stock information.
3 stocks is a logical choice.
Have I changed your opinion about most 3-stock arguments "all" based on feeling rather than logic?