Stop flaming him, he is absolutely right. Mr porter does many things right, but they are way expansive.
I hope you sent back the sweaters and bought them off the other website : it's the only sensible to do. Let them SUCK IT UP. They don't want to be competitive, it's their loss. In my opinion they try to compete with "fancy" stores (think Saks, barney's) but they don't realize that it is Luisaviaroma which is the king of upper scale e-retailling, and for good reasons. It's a different shopping experience.
They will never compete with brick and mortar stores, no matter how hard they try : you can't try things on, you cannot touch the material... In the end, the strength of online shopping revolve around prices and availability (sizes etc...)
Mr porter has no interest in that, they want to be luxurious and exclusive. Have a laugh and let them to their business model. Who cares about editorial content when you can have a better deal ? Use their website for measurements, ideas and details and buy somewhere else.
... Maybe they think they can become the next J.Crew
Luisaviaroma also ups their prices and their brand profile is a lot less versatile than Mr. Porter.