It can be tempting to point to what other chains are doing, and say “we should do that”. So let me give you an example of “we shouldn’t do that”.
The ICON network which has been around for many years said “Let’s deploy parachains on Polkadot” while maintaining their own chain, and created Ice and Snow. They put in a lot of development work and effort. Rallied the community. Only to learn a very big lesson (one, which by the way, a has lesson into why the cross-connected contracts narrative is a better approach). Maintaining two code bases, support, maintenance, and communities is incredibly expensive, time consuming, and fraught with risk – ICON cancelled the Ice and Snow projects after 1.5 year’s worth of work and I imagine at great expense.
If you believe in x-connected contracts, chain interoperability, MRL, and the Polkadot ecosystem as a whole, then it makes no sense to waste resources to deploy a Layer 2 somewhere else.