Leauge logic

At what point do you say that you have to all stay grouped in one lane due to being behind, yet giving up any possibility of gaining more pressure so in return to help relieve the pressure on our own team. There are times when im getting yelled at to come help yet I have a free open clearing to take a turret. I ignore them most of the time and get the turret then push one more wave and base. I feel im right doing so but I want other peoples opionons on this, very new player still but the common sense in this game comes very clear. Most people I keep playing with don't understand what a little bit of pressure can do for you team, and another thing is a lot of people I play with in normal drafts dot ever seem to focus enough on cs. Now my cs still needs work , and when I say work I mean my last hitting needs improvement. But I still understand the importance of early xp lead and gold lead. But it seems everyone just wants to play team deathmatch, I mean ive had games were ive gone 0/3/5 as udyr jg and im called complete trash, yet I was the only one who could push lanes and take turrets. Maybe im wrong, as I said im very new, talking pre season 6 new. The only form of moba im familiar with is Warcraft 3 reign of chaos, but this game just clicks. I also used to be a heavy WoW player, and to someone peoples disbelief, some of that information I was able to carry over. Such as your basic roles of support tanks and dps. Dot or HoTs, cd and armor. Damage mitigation and priority in fights. I mean how can someones logic be to focus a tank champ when the very meaning of a tank in gaming is to take the dmg. The supports should be cced while dps is peeled away. Then the rest should follow suite. I mean I watch people trying to win teamfights against a team with someone like raka, and not understanding that unless you are doing more dmg then she can heal, your wasting your time trying to fight anyone else and she should be primary focus for cc or death, I mean she doesn't even have to die, if she gets to low she isn't allowed to heal, this is the common sense I speak of. Please anything im wrong about here, tell me. If not, feel free to add any tips or anything for a new player. I need to learn every last bit of information that I can. Jg/top main using poppy /udyr.