I think it's needed only for complex networks where e.g. services are accessible from some but not all hosts. For a simple desktop computer, everything listens only for local connections or isn't installed. (Some programs imo need a nondefault configuration: OpenSSH shouldn't allow password authentication.) All uses of firewalls that I know need system-specific configuration, not a default.
Even if there are services available from other hosts, firewalls of your router and your ISP might prevent them from being accessed. (I don't have any professional experience nor qualifications related to networking.)
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