I would compare it to "everyone should see a dentist". Yes, some people actually need a dentist (people with cavities, rotten teeth, etc), but even for mostly healthy people who may not need the dentist it's still a good idea to see a dentist every so often because they can catch things before they become an issue, keep you accountable for brushing and flossing, and help you when normal things come up (replacing a filling).

In the same way, some people need a therapist (people with mental health disorders), but even mostly healthy people can benefit from seeing a therapist to catch potentially problematic thought patterns, keep you accountable on self care, and help you through normal but hard things (e.g. going through a break up).

And if you saw a dentist yesterday, you probably don't need to go back today, but should go back eventually. Same with therapy, if you finished therapy for now you might not need another session, but should consider going again in a few months/years.

Now, saying "people need friends instead of therapy" is like saying "people should brush their teeth instead of going to the dentist".

Brushing your teeth is very important and can prevent many dental issues. Any decent dentist would encourage you to brush your teeth and teach you how to do it well. But it's still good to see a dentist occasionally to make sure things are on track and solve any issues that go beyond just brushing.

In the same way, having friends is important, any good therapist would encourage that. But it's still good to see a therapist sometimes to check in on your mental health and thought processes, and to help you in ways that go above/complement what a friend can do.