No it is not. Beyond just feeling crappy, altitude sickness can put a person in genuine peril. My wife is doing a section of the JMT (High Sierras) this summer, and day one they supposedly start at about 9.5k and go up and over a pass that's about 11k. I have been reading her the riot act about acclimation. We are planning to pack into Steens Mtn the week prior to get her somewhat acclimated. I know some really cool spots from hunting it in the 8500-9300 ft range. We'll camp lower on the mountain the first day and fish and, well, acclimate a bit, then head up top and pack in from there.
We live at practically sea level so even 7k feet can give a me headache, nausea, etc. Though I will say, it's been a lot less of an issue since I kicked my aerobic baseline way up a few years ago.
