Not primarily. There were weirder CPUs in the past. Today's CPUs have largely converged on floating point operations. Basically just sin/cos/tan differ now.
It's possible to write fully cross platform deterministic code today, but it's harder to do and uncommon in libraries.
Writing state synchronization and using client side prediction is generally easier. Determinism is only necessary if there are bandwidth constraints.
Not so much easier but enables a different class of cheats in games where players don't have perfect information, even with other schemes there is normally enough information leaked that similar cheats are possible. OTOH using a deterministic simulation prevents a whole class of other cheats.
What class of cheats are prevented in deterministic simulation but possible with a dedicated server running a state synchronization netcode model? I don't think any...
It's possible to write fully cross platform deterministic code today, but it's harder to do and uncommon in libraries.
Writing state synchronization and using client side prediction is generally easier. Determinism is only necessary if there are bandwidth constraints.