It had many hardware upgrades over the years - upgraded CPUs, 128GB RAM, 4TB NVME storage, a modern AMD GPU, USB3/c, thunderbolt, etc
The only reason it got replaced is because it became too much of a PITA to keep modern OSX running on it (via OCLP)
Replaced with an M4 Max Mac Studio, which is a nice and faster machine but with no ability to upgrade anything and much worse hardware resale value on M-series I'll have to replace it in 2-3 years