Node count visibility is not a requirement for decentralization.
Decentralization is about who can control, censor, or unilaterally change the network—not whether you can run a public census.
Bitcoin node counts are estimates based on voluntarily exposed peers. Hidden nodes exist there too. Monero simply makes all nodes private by default. That’s a privacy tradeoff—not a trust requirement.
You don’t “trust” Monero’s decentralization—you verify it by running a node, mining, or transacting without permission. No authority can stop you. That’s decentralization.