My 2015 MacBook Pro with Broadwell i5 would indeed work "fine" for videoconferencing (in my case Google Meet), but it would also use most of a CPU core to do it. Which is fine if that's all you're doing. But if I wanted to share my screen and work on something else while doing so then it could quite quickly get to the point where I needed to start shutting down other programs, and even then it could cause lag when typing in less well-implemented apps.
My new MacBook with M1 Pro cpu it still uses most of a cpu core for videoconferencing, but it's a single E core and I have 9 others cores. Videoconferencing now makes zero difference to system responsiveness.
Most people won't need 8 cores, but I reckon the average office worker in 2022 would benefit from 4.
I’m just using Nehalem and Conroe as a touchstone that people understand in terms of cpu performance. That is what you get in general cpu performance, but it’s also got better media support and crypto acceleration and so on, so it’s more usable today. Actually a closer look at the numbers puts it just below Sandy Bridge i5 actually.
AMD cpu users (non-apu) and RX 6500/6400 owners obviously need to look elsewhere however. NVIDIA’s 1030 chips are ancient pascal based crap but AMD dropping encoder support on a chip designed during the pandemic era of work-from-home is a bit tone-deaf.
(Yes, 6500 and 6400 were designed during the pandemic, the architecture took longer to develop but 6500 wasn’t the lead ship in its architecture, and taping out a new chip configuration takes much less time than designing a whole architecture from scratch… AMD definitely knew it would be used as a desktop chip too. It was a deliberate space-saving move in the face of their wafer shortages, not something they got blindsided by.)