The line I use is "good enough is good enough". As long as your parts meet the needs of your application it won't matter if you have design headroom of 5% or 50%. Means that those full groove bearings might well get the job done, but I can promise you that they are not the best design for any performance application. Like cross drilled cranks - they work right up to the point where they don't, and then its often hard to decide where the issues lie if and when they do show up. Some high end racing stuff is running a partial upper groove these days - under 180 - groove does not even extend to the parting line.
Think of oiling like electricity. Oil under pressure follows the path of least resistance. When you feed oil into the unloaded side of the bearing it does not "like" to go into the highly loaded lower shell surface. It pursues lower resistance paths until they become saturated, where the flow area becomes a restriction that limits relief. It bleeds out at the parting line chamfer, at the eccentricity area approaching the parting line, and around the periphery of the shell depending on clearances. A full groove provides an additional circumference that doubles all these bleed areas into the unloaded area. Not a full loss since its not into the sump - but a reduction none the less. Coupled with a +/- 10-20% reduction in load bearing area for that lower shell.