I can confirm this. For me it was really not at all possible without additional utilities.
I pushed and pulled, massaged and tried to loosen, but nothing got me any further. I then pushed a guitar pick (got the idea from here and here and to me it seemed more gentle than a knife) into the crack you mentioned and “rolled” it (worked better than sliding) along the sides of the phone (by rotating it parallel to the phone’s screen, i.e. in the plane of the phone) from top left to bottom left and from top right to bottom right edge. Needed a bit pressure and slow rotation to avoid the pick jumping out (several attempts).
Doing this once was enough to then disassemble the screen very easily by the “magic move” (as shown in the Webinar video by Miquel or as described in the iFixit tutorial). No need to widen the crack (I’d be a bit afraid to do so and would suggest to be careful if this is necessary).
Btw, after reassambling, the second, third etc. disassembling worked very easily. Just do the “magic move”. 