I recently started a new character (actually kind of a remake of an older character but with some altered stats) and I decided I didn't want to build settlements or take Minuteman missions by the dozen.
So, in the beginning, I took dogmeat, got Preston and crew to Sanctuary (without agreeing to join them there). I avoided Preston like the plague while I built beds, water pumps, planted a crop so I can make "vegetable starch" and assigned Marcy and Jun to tend the crops. I also built defenses to protect my crops (and the people of course). Happiness in Sanctuary seems to be more or less leveled off at 30.
Now, I only go to Sanctuary to collect my taxes... eh, foods for processing. Home is a nice structure built atop the Red Rocket, I dismissed dogmeat, so he lives downstairs and guards the place while I am gone. He seemed lonely though, so I bought him a girlfriend and a brahmin, and they all seem to happy enough.
I built water purifiers at the Starlight, but nobody lives there.
I've built no radio towers at all.
So for game play, the effect has been that XP is a little harder to come by early on without the settlement quests. At the same time, I've discovered that I get the settlement quests by simply visiting the settlements without being a Minuteman... but I can get them at my own speed and when I want them.
Really, it gives the game a whole new flavor.