When you reply to a fun, closed, question on Facebook it doesn't affect you on a deep level.
It doesn't increase your connection to the organization or fellow likers. It has little influence on your future actions (and certainly not your buying habits). The only thing that changes are the engagement stats. They skyrocket.
If you were to look at VisitSweden's Facebook page, clearly they have high engagement rates. They have hundreds of people liking posts, commenting on posts, and even sharing posts. It looks terrific.
Therein lies the problem. It looks so much better and more active than their community did. They decided to close the community and focus on social media platforms.
If look at engagement metrics, this makes sense. Closing struggling communities is a good idea anyway. But it's mistaken to believe that the types of interaction are interchangable between platforms.
In dedicated community platforms people talk to each other, not just the page admin. They build relationships with each other. They visit daily to satisfy their social needs. This has significant, long-term, impacts on future actions and, yes, buying habits.
The FB page has few discussions. No-one is getting to know other people on the page. This is an audience, not a community. Despite all the engagement, it will be tough to demonstrate any measurable impact.
Interactions aren't equal. Interactions between members are very different from interactions with members. Responding to a Facebook post has a far weaker psychological commitment than participating in a discussion with other people. Likes have no beneficial impact.
You can look at the interactions themselves above. They don't bring the same value as discussions which take place in community platforms. They don't bring new value, new information, encourage high levels of self-disclosure, build relationships between members, nor build bonds between members.
This presents a problem for a community professional. You're going to get pressure to move to social media platforms. You're going to find it easier to develop a page that looks really active and pleases the boss. Yet you also know this page doesn't have the same impact as community platforms do. This is a really, really, tough argument to make. But if we don't make this argument, we'll find it impossible to build communities.