Games such as Red Dead Redemption 2, God of War, the Uncharted Franchise, The Last of Us (can include 2 if you want), the GTA franchise and many others support my point. They offer hundreds of hours of playability only from the single player modes thanks to rich open world's, rich narrative and great replay value. I have had Red Dead Redemption since launch day and still play it frequently to this day.
Now in some cases online multiplayer is fine but not in recent times. Take GTA online for example. In 2013 it was good but with the new updates and expansions it's not short of being unplayable with players flying across the maps and shooting you every time you spawn. Another issue is modders and tryhards who do their UTMOST best to ruin your and your friends game. I cannot walk in warzone without being sniped from the other side of the map or encountering campers. Single player is also more stable thanks to not requiring an internet connection and thus allows even people in Somalia to play without interruption. Also people are more peaceful as nobody in single player shouts or sings into a mic whilst you're playing. Believe me, we could all use some peace.
Lastly I would like to say this does not apply to all online games, but most. I'm not sure if this has been done before so if it has pls say and I'll delete.
Edit: some people are talking about co-op modes with friends. Co-op is great and I play it myself but playing with randoms is not so great most of the time as mentioned above. Co-op satisfies those who want story as well as those who want a social aspect in their games without the cons that associate with playing with randoms.