Yeah, because the QB was one of the slowest guys on the field. Elway was from the stone-footed drop-back passer era. QBs who could run were an anomaly - Randall Cunningham wouldn't really stand out much in today's league, but back then seeing a QB tuck & run was weird.Very different eras. The QB wasn't supposed to run in Elways prime because the defense would tear his head off
Mobile QBs didn't really start to become normal-ish until we were well into the 2000s. Vick showed that it could work, but even after him it was pretty rare for a team to use an early pick on a QB who they knew would run and then leave them at QB. We probably didn't really turn that corner until the last 10-12 years. There are still a lot more QBs picked who are a lot closer to being the stereotypical pure passer than they are scramblers (although that might end tonight).