A few things come to mind:

1. Posthog is the new kid on the block, so I think there is some level of belief that this newer version of what we already had will be better somehow. In line somewhat with your idea that this could be just a perception, and perhaps not a permanent shift.

2. The fact that it is built by a smaller team that doesn't need to define the product analytics category from scratch likely means product iteration will go faster, i.e. more features/fixes more often, and perhaps a more exciting roadmap. Posthog can stand on the shoulders of giants without being weighed down by all the tech debt that got the industry where it is today.

3. Posthog's pricing is much more up-front about what you'll be charged for; Amplitude & Mixpanel lean a bit more into the "contact us" flow aimed at enterprise orgs.

4. Posthog is open source, so if you wanted to, you could start with their hosted service and perhaps one day move to on-prem if your organization prefers that.