It's entirely viable. They spent most of the dev life buffing tall, at every point(though I still think wide wins out in a competitive sense)
The core of the idea is to use diplomacy as self-defense early, ascend very quickly, and then technologically dominate to the point any military or economic competition is pointless.
I would check your defensive pacts, the power of your allies if you're in a federation, likely enemies, on the diplomacy screen. If you're on solid diplomatic footing, you may not need the fleet at all. For me, fleet is all or nothing: either your strategy realistically calls for its deployment, at some point, or you should scrap it. It's an offensive weapon, if using it for deferrence, you've diplomatically failed, and should get allies.
Zardnaar is probably better versed as to the appropriate build and steps necessary to succeeded on that strategy. I'm very much the opposite type: I conquer everything around me. Right now, because it's the latest dlc(therefore the custodian team has yet to balance it), virtual ascension is extremely powerful. It limits you to seven planets, but you suffer no empire size penalties(which reduce research rates as a percentage). You would aim here for seven hyperdeveloped metropolis planets.