Actually there are very real ways in which this sort of thing can impact one vs another. eg. Adobe may push for a format that natively supports the double sided color filling rules they use in Flash to make it easier for them to produce Flash->HTML5 conversion frameworks without a lot of code rewriting while other parties may not have this as a concern.
That aside, you picked a ridiculously low-hanging fruit of a concern. Consider something larger, like JavaScript and the fate of ECMAScript 4 due to the very situation I'm talking about. But even the minor bikeshedding concerns can be used as political levers one way or another regardless of how (in)significant one implementation is compared to another.
There ought to be at least some things that literally none of the participants in w3c etc have any conflict of interest about and therefore would be able to decide quickly on. The debate over the <video> tag for example may never be decided on. But I have trouble thinking of any counter-examples.
That aside, you picked a ridiculously low-hanging fruit of a concern. Consider something larger, like JavaScript and the fate of ECMAScript 4 due to the very situation I'm talking about. But even the minor bikeshedding concerns can be used as political levers one way or another regardless of how (in)significant one implementation is compared to another.