That makes pretty good sense.
I live at an elevation of about 700'
If I go to Clingman's Dome in GSMNP at an elevation of about 6,600', I don't notice a big difference.
When I hiked the JMT coming out of Yosemite Valley, it wasn't until I reached 9,000' that I noticed the thinner air impacting my ability to hike (started getting very winded as the trail climbed from 9,000' to 10,000').