HTupolev

Largely yes. The most direct comparison would be between the 2005-era Alivio RD-M410 and the current "trekking" model Alivio RD-T4000. The basic mechanical operation is nearly identical, they've just lengthened the cage and changed to smaller jockey wheels. I've actually experienced both of these models on the same bike: my gravel bike had an M410 on it, and I switched to the T4000 to get a big more chain wrap. The new part doesn't really shift any better, and I didn't expect it to.

In terms of shifting, mechanical derailleurs haven't made any notable design advancements in a really long time. An Alivio from 2005 and an Alivio today are both basically just modifications of the Dura Ace 7400 from 1984, with tweaks to the geometry and spring tensions to suit them to 8/9-speed cassettes and wide-range MTB drivetrains.
Shimano's newer "Shadow" designs are a departure from the Dura Ace 7400 groundwork, but it was a departure made primarily to protect and stabilize the derailleur, rather than to improve shifting.

If you're looking at considerations other than shifting, current higher-level parts have made some advancements. For example, you can buy drivetrains with more rear cogs than were available in 2006, and some derailleurs ("clutched" derailleurs) have dampers on the a-pivot to keep the chain from bouncing around on rough terrain.

Aluminum bodies have never been standard at the bottom-end. Before plastic knuckles became popular, the name of the game was stamped steel.