No, they can definitely be activated at national rail stations with Oyster readers now. I have also updated my Oyster card at the machine outside FH station.
The only annoyance with the website updating is that you can only select dates in the future for your new travelcard e.g. if I wanted to buy a 7 day travelcard it can only start from tomorrow, wheras if I use the machine outside FH station the travelcard can start from today.