Instead of standing forever at mid throwing abilities in vain and gets hard engaged then blames the people not present, why not try to split push and take turrets? Especially when you know that you can't win 5v5 team fights but excel at smaller skirmishes. People are so braindead sometimes over "grouping" and "killing", forgetting that there are comps weaker at team fights but much stronger when they split and ward carefully.
As a split pusher you also have to understand what to expect from your teammates and the enemy team.
If you want to split, you either need your allies to have pressure and disengage (so if they send 2+ to you, your allies get something - if they 5v4 your allies they can get away) or your allies to have waveclear and safety to defend a tower.
If your team lacks good disengage and/or the enemy team has really strong engage - what exactly do you expect your team to do while you split? You even stated in your post "get hard engaged".
Like, should they just disappear from the map? You might have sufficient disengage or survivability to split and farm up there by yourself, but if they just sit in base to avoid getting engaged on, not only will you die 1v5 but they'll also fall far behind as they give up all the farm.
It's not just on you, and not just on your teammates. It really matters what the game state is and what Champions are there. Like, if the enemy team has Camille/sejuani/kassadin against your lux/miss Fortune/Sona - you really shouldn't be splitting. They stand no chance at avoiding that engage / tower dive.
Now if your team has Ahri/ezreal/Janna instead - that's an entirely different story (although without Janna or alistar it would be pretty tough to get out of Camille ult). If their team has Olaf/Lee/Anivia - likewise a different story where your team should be capable of avoiding getting engaged on.
As the person making the decision to split, you should be aware of how the enemy team can engage and what your team would have to do to avoid the fight.
this is and has mostly been a trait of low elo gameplay
