For a typical home user who isn’t opening ports or taking a development laptop to places with unsecure wifi networks, you don’t really need a firewall. It’s completely superflous.
A "typical" home user, whom I assume is less knowledgeable about technology, is probably the person who would benefit the most from strict firewalls installed on their device. Such an individual assumedly doesn't have the prerequisite knowledge, or awareness required to adequately gauge the threats on their network.
Anything you do to your PC that causes you genuine discomfort will more than likely be your own fault rather than an explicit vulnerability.
Would this not be adequate rationale for having contingencies, i.e. firewalls? A risk/threat needn't only be an external malicious actor. One's own mistakes could certainly be interpreted as a potential threat, and are, therefore, worthy of mitigation.
And if you’re opening ports on your home network to do self-hosting, you’re already inviting trouble and a firewall is, in that scenario, a bandaid on a sucking chest wound you self-inflicted.
Well, no, not necessarily. It's important to understand what the purpose of the firewall is. If a device can potentially become an attack vector, it's important to take precautions against that -- you'd want to secure other devices on the network in the off chance that it does become compromised, or secure that very device to limit the potential damage that it could inflict.