(totally agree with you—never used a "store bought" antenna.)
I shook my head and thought to myself "it's guys like that who make the rest of us look like loons for being in this hobby ..."
My only two professionally made base antenna's are my Mosley TA-33 and my Comet GP-9 that sits high, high, high atop the tower and serves as my 2m/440m DMR repeater antenna.
Everything else: homebrew.