If anyone is worrying about security, don’t use it for that, or at all if you don’t want, but it sure is nice to have that option if/when I want.
Seriously, I have multiple layers of security - extremely long & complex & unique passwords plus 2FA for banking, another (different) password and a PIV for work, etc. - and I really enjoy being able to get back into my desktop at a moment’s notice after grabbing a coffee. It even enhances security in several ways: e.g. by facilitating using a shorter time-out until the system asks for authentication, plus allows you to use a more complex password for your account, knowing that you won’t have to type the whole damn thing in 50 times a day. Also, even if someone had a literal camera over your shoulder watching you type your password (work? public space like library?), they would not get your fingerprint that particular way. Or if you really want to get paranoid (I don’t think Mac will let you do this by default without additional software though), you could require both password + fingerprint?
It is also worth noting that the issues for desktops are not identical to those of mobile devices: someone would have to gain physical access to my machine in the first place (afaik? now I wonder about that though… are the security credentials stored in a less secure manner that a remote intrusion could spoof more readily?), which is far less common than a mobile device that you take with you and is also smaller so more easily stolen.
Protect the stuff you value the most, but for the common stuff it is nice to have a quicker method of access. Like everything else, this is merely one tool in your toolbox that you can decide how & when to use appropriately.