I would say both depending on what bars you have, I have turned in on a low wall at the end of someone’s drive before (not in my T6) and the bars touched before the van, much rather have a scratch on the bars than the paintwork but let’s be honest they only mount on small brackets and it does take much to bend them so little impact protection from them but certainly can help on a scrape
Bigger rounder bars poke out more than say the new style VW T6 angled ones that sit much closer to the vans sills so some help more than others