IE hasn’t been the market share leader in a long time and couldn’t even retain compatibility with itself, let alone any ACID tests nor wider formalised standard

IE hasn’t been the market share leader in a long time and couldn’t even retain compatibility with itself, let alone any ACID tests nor wider formalised standards. And these days the problem is simply that the specifications are so complex and fail mode so forgiving that it’s almost impossible for two different implementations to output entirely the same results across every test suite. Neither of these are market leader problems. The former is just Microsoft being their typical shitty selves. While the latter is a natural result of complex systems designed for broad use even by non-technical people.