I mean I totally get your side that complaining isn't "necessary" but I guess it's because a replay system is not only considered standard to have in a competitive game, it is also just missing crucial features. But yes your argument wasn't about whether he was wrong or not, but moreso the fact that he complains and is negative and didn't even celebrate this small win. I would say again it is this case because it's similar to a phone manufacturer giving me the ability to text, when looking through the lens of only that manufacturer, it is a win. But when considering what every other phone manufacturer has, it should've already been a thing so it is hard to celebrate in that sense.
Lastly, Tenz can come off as negative and I do see why people are annoyed with it, but it is his intent to make the game better so I do applaud that. I don't really get the hate he receives for it though because it's all things people say/will say regardless, it's all just coming from one person in this case. But yeah I can understand where you're coming from.