You can either increase blocksize (and therefore decrease decentralization) or build L2s. Look at ETH with their big, frequent blocks. You can run a Bitcoin node on a 10 year old laptop, good luck running an Eth node with those specs. You need at least 1TB of space, and it's gotta be SSD, and you need a pretty fast processor. Which is why many Eth nodes are hosted in corporate datacenters, over half the network. You can split hairs over what counts as a "node" etc but the end result is the same: increased centralization due to large chain size/requirements.

Monero doesn't need L2s yet because it doesn't have the transaction load to fill up available chain space enough to impact decentralization. Long-term, we cannot store all transactions on every node and do that forever. Small txs do not belong on chain. I love XMRs approach to privacy, it will need L2s at some point. Or pruning, which comes with some significant tradeoffs.