Scotchloks were used by phone installers years ago, for water resistant connections in damp or potentially damp conditions (like under the house.)
They are bulky, not all that reliable (as I recall), and have minimal contact between the wire conductor and the connector conductor (meaning not really suitable for high current applications.) Plus they're fairly pricey when compared with solder and heat shrink (phone installers passed on the cost to the user in one way or another, so they didn't care.)
They are, however, fast to install; and for low current applications where bulk isn't an issue are pretty handy.
Forgot to mention that there is a wide variety of Scotchlok connectors, from simple wire nuts, to the flip connect (standard trailer wire kit) connectors/splices, to the silicone filled "waterproof" connectors. Make sure you look at what you're ordering if you go that route.