I think your post is really quite naive because it assumes in a two person friendship, one person has MH struggles and the other person has a positively great life.
Professionals should always be the first port of call if you’re in crisis because they have the correct training to be able to support you properly and help you. Friends and family have no such training and as a result will often find it difficult.
Friends and family also have their own myriad of issues in their lives that they’ll be trying to deal with. They may not be diagnosed with a MH disorder but they very well may be going challenging times themselves and simply cannot add more to their plate. Eg debt and financial worries, relationship/marriage breakdowns, health issues of another nature, perhaps one of their children may be having health issues or SN, grief, etc.
Friends and family will often take on more than they should because they care about the person who is struggling with their MH, but they cannot drown themselves trying to help someone else.
What would make you happy? If your friends provide so much support that they can’t sustain that they themselves fall into MH difficulties and develop depression?
I’m all for being honest and open when it comes to MH struggles, I’ve had them myself. But there is a huge difference between reaching out to a friend for support and talking about it, than needing them to hold you up every single day of your life. If that is the level of support you need, then you need to seek professional help. You cannot expect friends and family to put their lives on hold to be on call to you 24/7.
This is a fairly new thing I’ve noticed as well. Before people didn’t talk about MH issues at all (which was incredibly unhealthy), but we’ve reached a point now where there is a proportion of the population who feel that their issues trump every other person’s and they should be the priority in every scenario. In work, at home, in a friendship group. That is the scenario where people will step back because it is too draining for them to deal with. And that is a perfectly acceptable choice to make.