I had a profelx 859 (i think, big red alu frame made form round tubes, big pivot, carbon swingarm) was still going strong when I bought it in 2005 and felt very much like a yeti asr-sl does now.
Biggest improvements (IMO)
A bit more thought going into the design rather than pivots+bushings+spring= £1000 pogo stick
Fox float and vanilla shocks, now we had proper dampers
'platform' valves (abeit short lived, they seem to have died out now), now we could pedal the things.
Fox DHX5, over complicated, but worked better than anything else at the time. The current RP23 takes most of the valving though without the diving mid stroke.
CCDB then BOSS (or RS and Marz if your on a budget) Back to simple shim damping we started with.
I'd say more a series of incramental steps rather than waking up one mornign and all bikes were suddenly good.