Majority, everyone has it's own network, so called blockchain, but it has all the features, immutable and very very hard or next to impossible to hack unless some entity will pull what we call a 51% attack, but it is not feasible in the long run.

There could be crypto that don't have a blockchain but it's more of an exception than a rule though. One advantage of a crypto having it's own blockchain is obviously the trust, so it's better for them to have their own blockchain.