As someone who regularly works on a lot of projects at once or regularly context switching, I think this is missing the larger point here. Returns are not magically nothing for someone 50/50 on two projects, but there is of course a cost, and that cost increases with the number of projects, the complexity of the projects, and the pressure for delivery of the projects. It also varies person to person.

Going back to your original post:

> Yes but doesn't work that way, with context switching cost and all of the rest people who are 50% in one projects are not really that effective.

Again, person dependent but missing the point. Would have it been more accurate to say they have 1.4327 engineers on the project? Probably. Is that helpful when everyone understands what 1.5 actually means? Not really. And two projects is not so unreasonable depending on the situation.

> If anything, shows that they were not that committed to even put a resource dedicated to that project

100% yes to that. And as we have learned since this comment thread, it was not a 50% time situation but actually someone wearing two hats (PM and engineer): https://news.ycombinator.com/item?id=28426523