Having heard and sold many large Advents back in the day at Tech Hifi, many including myself preferred Ohm model Ls to the Advents. Those were designed specifically to take on the Advents but in a smaller package.
I still have my Ohm Ls that I refurbed myself a few years back. Also have newer Ohm Walsh and KEFs. Both are better. Have also owned Magnepan, B&W, Boston and others. Each were at least 1 up on the old Advents.
You can still buy upgrades for ohm Ls and most every other Ohm model ever sold since the early 70s. The upgrades take each up several levels to compete better with other more modern designs.
I’m sure armed with the right smarts one could take old Large Advents to a higher level these days as well.
Yes quality of home sound has advanced considerably over the last 50 years or so. Should not come as a surprise.