Depends.
In the US, most people simply get their phones from a carrier because it's just easier.
Then, some carriers, like AT&T, only provide certain "advanced calling features" to their branded (and locked) phones - like Wi-Fi calling or Hotspot. Sure, any modern phone can do those things, but AT&T will block those features from most unlocked phones on their network.
At least T-Mobile is much more BYOD friendly. Unfortunately, T-Mobile is not much of an option where I live, and Sprint wasn't much better. So, combined, they have slightly less horrible coverage here.
I personally never had an issue using AT&T since they were Cingular back in the late 90s with my first flip phones. I also never relied on them for device issues, preferring to deal with OS updates on my own.
This was easier on my BlackBerry phones since you could obtain and load a newer OS than what AT&T provided for both the old BBOS and BB10 phones. I did this from 2007 to 2017 when I finally retired my Z10 for a Galaxy S8. I worried at first about how to update outside of AT&T, but it was around that time that locked phones were getting updates at the same time, or earlier, than the unlocked models. Of course, this fluctuates now, but I've never felt put out by an update that might be 2 months late. For their BlackBerry phones, AT&T could be 6 months to a year and a half behind the latest BlackBerry released OS version.
Point is that depending on who you use as your carrier, and what you want out of it, carrier locked is just easier to deal with. There's very little advantage, in some cases a disadvantage, to using an unlocked phone. As long as you have no plans to bounce around different carriers, or travel out of the country a lot.