Those "professionals" you know have no clue of what they're talking about unless you're misquoting them. And to each their own, not saying any 2 answers will be the same, but from my experience the main software choices among professionals(as in guys mastering material released through labels commercially) for mastering are Samplitude/Sequoia, Cubase/Nuendo(ironically the same company that makes Wavelab), and of course, Pro Tools. Not that it matters since mastering can be done in any program that can load a stereo wav/aif file onto a track where effects can be chained...might as well say any DAW out there, even Garageband.
Wavelab, Toast, CD Architect, Quattro, ect while labeled as "mastering software"(and can be used)are more so for arranging and finalizing a tracklist/order with fadeins/outs, ect. for a CD(which is very much a part of mastering, but not the part being referred to when we're talking about processing individual songs). Most M.E.'s do their work within a DAW with tons of outboard gear for support.
If anything, properly done mastering fixes dynamic issues and makes your song more amazing, not the other way around. Never heard of a "professional" who would disagree with that statement.