lol what is this a fight at the kids playground?
of course a modern site will crawl on an old pc while scrolling. Thats my point of hardware limitations. Fast forward to today and we have image editors, music editors, word processors, etc through the browser. Are they as advanced as a native client? Of course not.
However as stated below we have overcome previous limitations in the past and this trend is only going to continue.
Heck I have even rented a mac once from a streaming site and it performed well with everything except file transfer. Thats just limited by usb and internet speeds which are only going to get faster.
Honestly I wouldnt be surprised if the os on the devices we use in 20 years strictly connect to the cloud and the entire desktop is streamed in real time to the device