Well, I was used to that requesting the seat in advance is difficult with some airlines. And you would have to do the online check-in early enough to get your favourite seats (I prefer aisle seat). That was the case at least sometimes with SAS ...

My surprise was quite big when I got two of these heavily discounted (Z class) tickets to Beijing last weekend. When I received my ticketing information couple of minutes later, I had my seats assigned and even bigger surprise was that all my seats for those four flights were aisle seats.

What is even more surprising is that I informed then my BAEC number when purchasing those tickets - so how did they knew that I want aisle seats? Yes, I have my Finnair Plus account still active and my profile states that I prefer aisle seats and my BAEC profile also has that information. Did they search using my mobile phone number or are they actually able to read my BAEC profile and actually use that information for something good? I am impressed anyway.

AY has used seat assignments for all scheduled flights already for some time. I wouldn't be totally surprised if also Finnair could see your OW profile as it for sure works the other way around. Other OW airlines clearly get the profile information via the AY Plus number.

If only could AY assign exit rows/bulkhead in advance also...as discussed separately here as well...this current system in from the 70's..