I don't mean to be a dick but without giving actual reasons all you're saying is "I preferred ow1", which is kind of what my original comment was referring to. Tank synergies is definitely something that was lost with ow1, rein/zarya and dive comps were very fun and definitely something I miss. But it was also a major source of balance issues and player frustration.

Two tank team composition was a consistent balance issue and severely restricted the design of tank heroes. Sigma is a really fun and interesting hero, but when he was added overwatch entered a prolonged two shield meta which was incredibly boring. The devs added a cool hero, and he made the game worse. Not only did he make the game worse, but there was no obvious or easy solution, because sigma wasn't the problem, two shields was the problem. In my opinion that exemplifies how bad of an issue the game was facing and justifies the changes made.

There's nothing wrong with preferring ow1 but the person I responded to called it "a terrible game compared to the original" which is just blatantly incorrect in my opinion.