Things like this just make people feel even more worried and anxious and nervous about what to say to a grieving person than they already do. This makes people avoid saying anything at all, and some people actually avoid the bereaved person because they are so uncomfortable with the potential intensity, isolating the grieving person and making them feel even more alone.It's terrifying for many, the worry of saying the wrong thing and making things worse, but you know what grieving people REALLY need? Just to know that you care.
I've been bereaved before, my mother died nearly three years ago. I volunteer for a suicide line, I have a counselling qualification and I've had bereavement counselling. I'm not trying to brag because I'm very much as much of a novice as anybody else in this area but that's where my opinion is coming from.
I do agree that people should never say 'I know how you feel' because you can NEVER know how somebody feels. As an example, my mother died... a friend might try and comfort me and say 'I know just how you feel, I felt that way when my mother died' but they can't know how I feel because they were different reasons for dying, different relationships between us and our parent, different life situations, everything's different. It can be a little offensive to some people for another person to say that they know how they feel, when they actually cannot know at all. The best thing to do is to try and empathetically find out what the person is feeling, calmly and without judgement, and give them space to express how they are coping and what is running through their mind. But of course, I know people usually say this because they want to comfort, they have the best of intentions.
I also agree with the 'stay strong' stuff. Man, that is frustrating. The worst thing anyone said with the best of intentions was 'pull yourself together, your mum wouldn't have wanted you to be like this because of her'... that made me feel that not only was I being pathetic, I was letting her down too. It places a lot of pressure on people to fake that they are okay when they're not, and they might feel as though they are letting the side down if they ever acknowledge how bad they feel.
When I lost my mother it took literally about six months before I started to properly, really grieve. And then it was a solid year of hell, total pain, crying so hard I couldn't breathe multiple times a week and total numbness and sorrow the rest of the time. The best thing my friends ever did for me was just to be there. I really appreciate the ones that didn't dodge it, that didn't avoid it for fear of upsetting me. Nobody who has lost someone close to them is going to have it far from their minds, so mentioning it isn't going to make anything worse... it shows you acknowledge their grief, and that you are aware things are difficult for them. Slapping somebody on the back and taking them out to 'take their mind off it' usually is counter-productive.
All I appreciated was those people who remembered throughout those horrible eighteen months that I was probably still suffering and that while time was passing, I wasn't necessarily feeling better. It got worse and worse for months before it began to improve. I valued people talking to me about her and asking me stuff about her life and what she was like, people who wanted to see a photo of her or know her name if they'd never met her, just a simple text saying 'hey you, how are you feeling today?' meant everything to me!
There are no easy answers and people almost always mean well. I liked people coming over to hang out so I wasn't alone but also people respecting when I said I needed to be alone. It's good for people to ask 'what can I do for you?' rather than the 'if there's anything I can do, let me know', for example my best friend's mum paid for the funeral food as we couldn't afford it, my best friend, she bought me a bottle of my mum's signature perfume randomly so I could smell it and be close to her, I was living with a partner at the time who took care of meals because I was never hungry and couldn't bring myself to eat for a bit.
Just be there, be present, show that you care and that you're not going anywhere while they go through their pain.