If only 3 words wasn't a proprietary black box, which demands that you use their service / api and that you are not allowed to reproduce it without their assent. Plus there's a bunch of other drawbacks to w3w if you just search a bit online.
At least the algorithm for plus codes is known and can be reused even if Google decides to drop it in the future.
A system that depends on a functioning proprietary API to resolve coordinates is idiotic. That’s so unreliable that it can’t be used for anything more than an ephemeral exchange. At that point you might as well have a 3 word url shortened link.
I prefer an unambiguous and open way of communicating locations on the surface of the Earth, to a proprietary service from a company with a long history of pulling the plug on products.
Clicking on a map location in Google maps shows a context menu where the first entry is the latitude and longitude, click that and it copies it to the clipboard. No need to use a Google specific encoding.
I'm not sure that using Google Maps to demonstrate copying a single way of encoding coordinates vs using an open standard is a terribly convincing argument.
Having a field that takes lat and lon has all sorts of ways to enter data either incorrectly, or in an unexpected format - if someone has coordinates from some other source they might be typing it in, rather than copy/pasting.
Also, as others have mentioned - plus codes (or Open Location Codes) are an open standard that can be implemented by anyone under an Apache 2.0 license with a whole bunch of example implementations on github[1]
Find the place on Google Maps, copy the plus code.
Rather than entering lat/lon coords... except did you get the sign right, or maybe you flipped lat/lon, or got a significant digit out.