Because it is better than them! How many times are we going to go around and around this point? You even tacitly admit as much throughout this thread.
Your own distaste for them doesn’t discount the fact that the M60 and Centurion derived tanks make up a sizable proportion of the 8.7 MBTs, with many of the others being similarly poor in comparision to the A1A1 (Cheiftans, T-62, ZTZ59D1, Object 435, etc). Really, the only ones that are close are the Type 88s
Date of introduction, and what vehicles a certain tank was designed to face, have no bearing on what BR it is. All that matters is how strong it is in game. The A1A1 has everything it needs for it’s playstyle to make it substantially better than all other 8.7 MBTs by a substantial margin. It belongs at 9.0 on the basis on it’s own strengths and weaknesses.
Let’s take a different approach and compare the A1A1 to other 9.0 MBTs. Surely, if you contend that it belongs at 8.7, that means that it’ll be clearly weaker than the 9.0s?
First we have the TTS(s). Such poor tanks that Gaijin is literally restructuring the tech trees to put vehicles behind them in order to convince peope to play them. No content.
Then the XM-803, which post the dart nerf is just pretty sad. Still, nice to see something that can actually compete with the A1A1’s mobility. But yeah, equal mobility, worse firepower. It’s a wash.
Then the T-62M-1. Like the T-55AM-1 on a better chassis with a better gun, yet still held back by the slower mobility, worse turret traverse and gun depression. It’s close, but I’d still go with the A1A1.
Then the Cheiftan Mk 10. Hah. Maybe in a different meta. No contest.
The later Type 74s are a good matchup. Similar mobility forward, but much worse backwards after the nerfs. Worse gun handling, effectively worse gun depression when you don’t have the time to use the suspension. Better firepower. LRF. Similar armor. I’d maybe give a slight edge to the 74s, but it’s still close. The A1A1 is more comfortable to use due to the reverse speed and accessible gun depression.
The OF40 Mk2 is also close. A slightly slower, slightly larger Leopard but with a LRF. Similar to the 74s, I’d say it’s arguably better, but again, it’s totally close enough to share a BR. Italy needs every W it can get.
And finally we get to the Magach 6M. And we’re back to no contest.
So there we have it. At 9.0, we have 3 tanks that arguably beat it, 2 tanks that are too close to call, and 5 that are so much worse it’s no contest. Sounds to me like a pretty balanced tank.