Not so at all. I just bought JFK-MXP for about $500 on AA and upgraded directly. There are tons of JFKLHR fares for about $500 one way as well. JFKMAD is $536 all winter long

I think what the OP is saying and I have noticed this too, is that until recently, many one way fares have been very very cheap to Europe. I've bought several tickets in the last few months for $400 or so on both DL and AA. However, in the last week or so, the one way pricing seems to have largely returned to pre-pandemic craziness in many markets that previously had some very low one way fares such as CDG, FRA, AMS etc.