Yes you can. All you need is your PNR and the surname.A skywards account is not needed.However you will be surprised at the number of 'sheeple' who dont bother reserving seats especially in Y

Someone I know was complaining that Emirates separated her mom from her on her last flight. I enquired whether she had selected seats for this trip (planned months in advance)and the answer was no.

Quite a few know that you can select seats but don't bother !