No, in fact, triple monitor is IMHO even better, as in most workflows it will allow room for reference materials on one and palettes/tools/readouts on another, in addition to what you're working on.
Other benefits include:
>works better than fewer larger monitors for programs that take over entire screens or DEs with bad window management, particularly media playback and vidya.
>allows separate LCD & CRT displays, for their respective strong suits of text/lineart & photos/video
>simultaneous landscape & portrait displays, plus multiple portrait displays, more important than ever with the unavoidability of 16:9 monitors
>if you have an exotic rig, such as multiple sources using KVM switches, PCIe passthrough, etc., it's way more convenient to always have a display for your primary environment available.
>the reverse is also true if you have multiple exotic displays, like a front projector or VR helmet, where having an extra conventional monitor to mirror it can be very handy.
Maybe, in the future, giant curved monitors and much better designed DEs with more standards-compliant software will render multiple monitors mostly obsolete, but we're not there yet.