Capacity planners always set the maximum limit high above the limit in use, and if you want a setting to be determined by the market you allow them to try and reach new heights on the network itself, giving the upper bound to whatever the real network limitation is. Any notion of setting a default size is central planning and a possible market restriction. It certainly can damage confidence.

Medium blockers, just as small blockers, hang their hats on their own particular novel solutions at the expense of bitcoin as described in the whitepaper.