Not necessarily — 700c is the most common wheel size for gravel bikes and works great for the majority of riders. It's the same diameter used on road bikes, so you get better roll-over performance and faster speeds on smoother gravel and paved sections. Tire selection is also much broader in 700c, giving you more options at various price points.
A 700c-only frame really only limits you if you want to run very wide tires (47mm and up) for rough terrain or bikepacking. In that case, 650b wheels let you fit wider rubber within the same frame clearance. But if your typical rides involve gravel roads, fire roads, and mixed surfaces with tires in the 35–45mm range, 700c is ideal.
If you're mostly doing gravel racing, fast group rides, or weekend adventures on moderate terrain, a 700c-only bike is a solid choice — not a compromise.