I suppose, and you may be right. But I meant that the Half-Life series is a very cinematic (among the first games to embrace this, if I recall correctly), right from the intro. Playing just HL: Alyx would be like watching Return of the Jedi while skipping A New Hope and Empire Strikes Back -- I mean, you definitely can and still enjoy the movie, but you're missing something important.
They could just as easily take a similar route. And they should, because it's on a different medium.