You are again repeating the only argument that helps your narrative while disregarding at least a handful of others that clearly don't. I think I've read recently a post of yours, where you accused a poster of doing the same and you blocked him because of that. You are being contradictory here.
Again. There were 3 ITTs in that Giro. Roglič won 2, Campenaerts zero. The debate should normally stop here. But OK, I'm going to explain a little further.
Of course you've decided which is the main ITT and which ITT is "hardly a reference". I can counter you by saying that you are wrong. The ITT on the first stage should be the most telling one, because the riders are still fresh and actual time trialing ability counts the most. In the other two fatigue and regeneration were a big factor. Roglič was battling for the victory in that Giro, Campenaerts came in the Giro to save energy in all the stages and went all out only in those three ITTs.
Your comparison with Quintana and Ganna is...let's say funny. I know you were exaggerating there to make a point, but it's not a good example. With Roglič and Campenaerts we are talking about riders with similar ITT level at the time. When deciding who is better you clearly search for some kind of tiebreakers. Wins in ITT stages is a sound tiebreaker to use in this situation. Again it was 2 wins to zero. I should also mention that both riders took part in the Tour de Romandie a week before the Giro and guess what, Roglič won the ITT where he destroyed the competition including Campenaerts (who was btw second).
Let's bring up Victor's mechanical. Yes, he had a mechanical in one ITT stage of the three in that Giro. He lost about 20s there and lost the stage by 11s. So he probably would have won without the mechanical. But this things happen. It's part of the sport. It will happen again. Like the changing of weather conditions for the riders. Some are lucky and ride on dry roads, the others are unlucky when it starts to rain and have to ride in wet conditions. And that's exactly what happened on the stage Campenaerts had a mechanical. He was lucky to start on dry roads and ride the majority of his ITT on dry roads. The riders towards the end of the start list (Nibali, Mollema, S. Yates, Roglič, Conti among others) didn't have this luxury. I'm confident in saying that Roglič lost more time because of wet roads than Campenaerts lost because of the mechanical. I posted a highlights video of the stage where you can clearly see the conditions for both riders in consideration on various parts of the course. But you don't care about that, because you see what you want to see. If you want I can post you a Tiz Cycling full stage video, where you'll see that some drops of rain started coming down when Campenaerts was already at 7km to go on the uphill sections. On the other hand Roglič had wet roads for the entire ITT and rain for 95% of it. Multiple riders who rode in the second half of the startlist in the post race interview said that they had to go super slow in the first part because it was slippery and a lot of puddles on the rode. Roglič was one of them.
I'm not by any means comparing their careers as TT riders. I'm not going there because I think I wouldn't be able to decide. Campenaerts is a purer ITT specialist, better on the biggest events lately, while Roglič has more ITT wins. I was talking only for their performance in the Giro 2019. There's no comparison really and I think any objective person would say the same. I'm not expecting you to change your mind because of all my time here on this forum, I've happen to notice how stubborn of a person you are. You rarely (if ever) admit, that you are wrong. And you've been wrong before believe me. You are still a good poster and I like to read your takes. So don't block me, please
Anyway, this discussion has gone too far. Campenaerts shouldn't even be the topic of conversation here. OP was talking about best ITTers among GC riders. That's why after Roglič he mentioned Almeida's ITT performances from the 2020 Giro.