This is exactly it. Especially for the UK offshore projects where sites were auctioned off: All bidders knew that a competitive bid had to aim for an ROI only slightly above market rates, given that risk was very low. This means that 1 percent on production will easily turn into 10 or 20 percent on profit.
Source: worked on CAPEX and yield estimates for major player operating in this sector for a decade.
Did they factor in the risk that a site upwind of them could be auctioned later basically turning their project unprofitable? If you bid higher ignoring this risk and later lose money, maybe they should have bid a little less