Sometimes it's more profitable to refuse to give people something that they'd pay for. I'd put money on things like Oculus being used to paste ads all over comforting landscapes instead of eliminating ads. I wouldn't be surprised if eventually using Oculus devices to modify or remove ads ends up being explicitly against the ToS, and being caught risks bricking your device and getting you banned from all Meta owned platforms
Most billboards are designed to be visible on interstates and highways, where wearing VR goggles wouldn't be allowed.
As for "removing ads", why would an ad company like Meta do that when they could get paid more to dynamically replace static billboards with targeted advertising delivered through goggles?
Who controls what gets to be sold on the Oculus Store? Do you think the advertisers that spend billions on FB/IG are going to be OK with Meta trying to eliminate another advertising channel?