I'd have to disagree. At low elo, putting full faith in your team that if you build full utility they will carry you is to be frank, a crapshoot. That said for the most part I do build more traditionally with support/utility items. Perhaps i'll add on an ap item like Rylai's on Nami which gives good sticking potential for chases or peels.
Sona however is my exception. I've built her full utility. It's boring, uninspired, and honestly limiting. Part of being support is the fact you do want to inspire terror into that enemy botlane. Support doesn't meant you're "just" the ward/cc machine. You are potentially just as much of a threat. AP Sona (always with a full support item/Sightstone) is a fantastic lane bully. It's fun, and it more often than not, makes sure I win games.
Perhaps at higher elos, you can just sit back as an active items machine, but i'm not anywhere near that yet. I'm expected to not only provide vision, deny vision, peel, set up potential kills, but also output a fair amount of damage as well. I've double killed solo on a full utility Nami, and gone on killing sprees as AP Sona. There is nothing wrong with either kind of buildpath for support.
There is room for all supports in this game. A mage that has enough utility that can be fit into the support role is not a bad thing. It diversifies the game. No different than champs finding a different role they work in besides their default. Perhaps some people just don't like working around it or want support to be weak. I think all 5 members of the team can and should be strong and a united front.