Matic was originally designed to use plasma. That might not have worked out like how they thought it would, since they recently rebranded to Polygon and announced their intention to become a SKALE-like network of blockchains. While they’re apparently only now pivoting towards that, SKALE has been in development as a network of blockchains for years now. For what might be a better comparison right now - there are currently 3 maturing “network of blockchains” projects: SKALE, Polkadot, and Cosmos.
Jack and Stan have talked about these 2 other projects, and more here: https://t.me/skaleofficial/151441