It's possible, but highly unlikely. Same with the OBP. Sure you can come up with a hypothetical scenario in which a team has 27 walks and no hits, 3 walks per inning, no sac hits, and they don't score a run. But as you already pointed out, a team with a .500 OBP has an expectation of over .600 SLG, so the reality is that they're scoring a ton of runs. The real question is if we take a very good, but not elite, offense - say a team with a net .350 OBP and .450 SLG - which is going to contribute more runs to that offense, increasing the OBP by 10 points or increasing the SLG by 13 points? I would contend that the OBP would add more runs. Bill James would say the OBP adds as many runs as 18 points of SLG, so that would suggest the OBP helps more. The same applies to an average offense. Over the past 60 years, a rough estimate of an average offense is .320-.330 OBP, .380ish SLG. These are still in the range at which we'd expect similar gains from adding OBP or SLG. So for an average-good offense, adding OBP is more valuable than adding a commensurate amount of SLG.