Yes it is. That's why I don't bother to iterate in to an ideal stem length.

To expand further, for me fit isn't so much about actual stem length but how my body is stretched out. I suspect without measuring that my body and hands are more or less at 45 degrees from horizontal. But 45 deg or not, moving the hands closer (or further) means I'm stretched out less (or more). The hands being moved closer either from a shorter reach stem or by raising the stem or even by re-positioning the levers or rotating the bar slightly all do almost the same thing. Because the HT is angled back whereas the stem is horizontal, raising the stem 1cm should make slightly more of a difference than a 1cm shorter reach.

Now there are differences. If you compensate for a shorter stem + TT by lowering the bar, you correct your body angle but your arms will be more vertical and carry more weight. That's why you can't totally fix a short TT with bar height alone. So if you then choose a longer reach stem it moves your arm mass further in front of the steering axis, which should improve dynamic stability. (At least, it improves mine.) So this is a win-win choice.

But once you get the stem reach in the right ballpark the difference between a small stem change and a small bar height change becomes less significant. Which is good because swapping out the stem is a PIA.