Thanks for the comment, and you're right, modern computers do have a much better architecture! As I was laying out the story I was thinking about what it looked like when we started. I'll clarify that in the image caption that it's from that era.
There's usually enough for a GPU, SSD or two... and that's about it. I don't like having to spend so much for fast IO, dangit.
Can sometimes find boards that do switching to appease :/
A B650(E) board has enough lanes to give you a fast GPU slot, four CPU x4 slots running at 8-16GB/s each, and four chipset x1 slots running at 2GB/s each.
The ATX spec allows for 7 or fewer physical slots. That's not what's letting me down!
How many lanes are actually available and their division changes over time. Everything from USB to SATA has internally been moving to PCI-e, there's more 'internal consumption', too.
Gen5 is kind of a victim of success. Each individual lane is very fast, but providing them to a fair number of add-in cards/devices isn't practical. Simply physically, but also bandwidth between lanes.
Pretty much all of gen4 is nice, those systems are perfectly viable. More lanes that were slower offered me more utility. It's multi-faceted, I overstate it too. I like hyperbole :)