Or how weak Origi is ?
Unlike how Italy made use of the 5 sub rule, English teams have always considered that to be a temporary thing, and that leagues will revert to a 3 sub rule once COVID is over, and thus didn't want to indulge like other leagues to get use to rules that may one day go away.
If that means you only get one sub in every department, then Mane would come before not just Origi, but almost every other attacker in the Premier League.
That's definitely not a testament to Origi being weak, but just weakER than Mane.
Origi could still tear Milan a new one, so considering that, he's better than most options that Serie A have to offer.
Milan are still not there yet financially to be bringing in top talents like Mane or Salah, so a step down like Origi isn't really a bad option.
As always, trust Maldini to know how to pick and choose undervalued talents. He's done well enough with Theo, Hauge, Tomori, Alexis, Tonali, Bennacer and Kalulu hasn't he?