Double and Triple pawns are no liability

[hgm]

When the number of Pawns stays the same, each extra doubled/tripled/multipled Pawn also means an extra (half-)open file. These can provide some compensation. Especially if there are Rooks around that can profit from this. Note that in the given position all Rooks are still present. The half-open files make white's Pawn structure suck, by having several 'backward Pawns'. So I don't think there is very convincing evidence that doubled Pawns do not deserve some penalty. It is just that this penalty can be exceeded by associated bonuses in favorable cases.