A rising tide lifts all boats. Maybe "most valuable tech company in the world" would be a more convincing argument, since the tide receded shortly afterwards.
At the time that Cisco was top of the world, there were plenty of other high profile tech companies -- Microsoft, IBM, Intel, Sun, HP, DEC. On the networking side there were 3Com, Nortel etc. They all rose the tide of the dotcom bubble, yet Cisco came out on top. You should wonder why.