Are there any examples of businesses that had a network effect moat but was still dislodged?

Product or service that becomes more valuable as more people use it, whereby the *value of the network* itself becomes more valuable than the product or service itself

This becomes a moat because any competing product or service can no longer compete on the grounds of a *better* product service alone

Certainly. Myspace is a classic example. It once dominated the social networking space, benefiting from a strong network effect, but was eventually overtaken by Facebook. Facebook's better user experience, innovative features, and strategic expansions allowed it to surpass Myspace's initial lead.