" don't bother solo or pool mining if you have old equipment, just buy coins instead",
if you believe in bitcoin why not ~ mine to a solo pool or a smaller pool to make a (tiny) impact against the centralisation of the big mining pools.
If everybody had the current attitude in 2009-12 there is no way that Bitcoin would be where it is today, if it wasn't for early miners, 10,000 pizza guy, ~
Your statements about other stuff like running node, using over the counter methods to buy, etc. are correct but not the ones about mining.
You can't compare mining today with mining in 2009-2012. Back then you only used the PC you already had without needing to purchase specialized hardware. Meaning you could mine using your CPU and later with your GPU. Today that does not work. You need to purchase ASICs to be able to mine bitcoin otherwise it is not worth it because statistically speaking you will not find any blocks due to the high difficulty.