One or more players are doing this dungeon for the first time.

[PotatoWafflez]

If they are too lazy to ask at the start of the dungeon, they have all the trash up until the boss to ask, if they don't they probably won't read it anyway.

Even then most tactics are simple and just require some common sense and observation there is no excuse to not pick them up mid-fight.

Not to mention why would you want to spoil a fight for a newbie.

TLR not a babysitter stop expecting other people to spoon feed players

[T2teddy]

Well mister food and drink lover, maybe said new player might appreciate not spending the whole boss fight dead on the floor? I mean hey how hard is it to say watch for Mortal Gaze and turn your back , and switch to the other colour of floor when you see its divided into two colours? Easy peasy.
Or as another example the yeti in snowcloak. Don't attack the spriggans, do attack the yeti and the haplit?

Information avoids needless wipes or overly long fights.

Just sayin'...

[Ralvenom]

If they are too lazy to ask at the start of the dungeon, they have all the trash up until the boss to ask, if they don't they probably won't read it anyway.

This.

It's not the group's fault if the new person doesn't get how to do the boss.