If the Scottish parliament had not been elected with a broadly proportional system, Labour would have won a majority with less than a third of the votes. Similarly in Wales, without a proportional system, Labour would have had a clear lead in seats with no more than a third of the votes.
This would have been far worse than a wrong-winner election (a.k.a. plurality reversal). Those happen frequently enough in our own country and others with winner-take-all like New Brunswick, Canada last year.
Read it again. A majority of seats with fewer than a third of votes.