Why is event sourcing usually paired with CQRS instead of being used entirely on its own?

Event sourcing on its own is genuinely bad at answering simple read questions like 'show me this customer's profile,' because answering them could require replaying potentially hundreds of events just to reconstruct current state. Pairing event sourcing with CQRS solves this cleanly: the write side stores events as a perfect, permanent history, while a separate query side maintains a fast, ready-to-read copy that's kept up to date by listening to those same events as they happen. Each side ends up doing the job it's actually good at, rather than forcing one model to be both a complete historical record and a fast, queryable snapshot. This is why so many production event-sourced systems adopt CQRS alongside it, even though the two patterns are technically independent and neither one strictly requires the other.