Norm in mobiles?
"Initially there would have been no way to deliver anything sensible without it. In the days of GPRS (and Edge here and there) the bandwidth of an average mobile connection pretty much required re-writing web pages. The "other uses" came later."
Not quite. Initially there was WAP/wml which the sooner we forget about, the better, but that was designed to create custom "web" pages on small screens with the bandwidth limit on GPRS. It wasn't http/html so can't really be considered interfering or rewriting (although that technically happened - wml was converted/compressed to bytecode by the WAP gateway).
All the while though, GPRS/EDGE was also capable (and did) provide a "pure" net connection, with no proxies or interference on internet connections. Using IRDA or Bluetooth I regularly used my mobile as a modem - initially as "dial-up" (you could use it as a 9.6K dial-up modem to any ISPs numbers), then as a pure GPRS or EDGE connection directly through an APN, you even had your own IP address and it would permit any traffic. Part of the reason Opera Mini took off was because it would compress images/html etc. I'd say it was around the time of 3G taking off when network operators started introducing the closed model with Opera-esque NATed/proxied content with content re-writing.