Softs give you better traction off the line. So good launch and you jump either Max or Lando (depending on their starts). Then an early SC (which is much more common than a late one) and you are in for new tyres and maintain position if you are lucky.If you are betting on a safety car to come, you want to stay out as long as possible so you can do your pitstop when the SC car comes, rather than doing it before. So you need the Medium tyres.
And maintain what? If Lewis has a good start, Lewis cannot defend against Max when Max has superior Medium tyres. Lewis could have only maintained his position against Max if he gets a good start on the Medium tyres until a potential safety car comes.
It’s interesting to see that Lewis as a 7-time WDC has to fight the night before the race explaining Mercedes how the soft tyres will not work (and he is correct) and gets totally ignored. While George with far less F1 experience gets to make his own strategy decisions as what we see during the races.
In the end, it doesn’t matter as Lewis said he is now “done with Mercedes” (I don’t blame him). And he has a good chance of beating Mercedes next year if Ferrari will remain as good as they are.
I believe that was the strategy.