For probably the last 3 or 4 years now, Riot Games has based everything (balance, champion design, etc) around team play. Many of the abilities and concepts which players used in the past to "solo play" have been reworked, toned down, or flat out removed. Ranging anywhere from raw stats, to items, champions, to dragons and barons, many things that Riot has adjusted have been ensuring that players are required to play with their team to be successful. These days, when one player gets ahead, it's very likely the entire team is ahead, and then the latter... When one player is behind, it's more than usually the case that their entire team is behind.
This mentality that Riot has been pushing is unhealthy, and creates quite a lot of frustration. Some champions have many things (most modern reworks) and then other older champions are put off or intentionally left weak. A good way to picture this better is to simply compare old Warwick with the reworked version. Before he was reworked, Warwick was a solo play champion. He farmed, got his items, tanked up, and tried to make plays when his ultimate was available. He had a lot of down time between ultimates, which enabled good counter play for enemies. Post re-work, now Warwick has a dash on his heal, gains large global movement speed, has damage reduction and a fear, and his ultimate has even more range than previously. All of these things being added to enable Warwick to get involved more with his team. Most champions who haven't been reworked recently are on par with old Warwick, yet left competing with the likes of newer champions and re-works on scale with new Warwick.
I've been playing quite a lot of Middle lane (and Jungle) recently, simply because as a former Top Lane player, who was a Riven main, I began to notice the effects of Riot's "Team Play" mentality on Top lane in particular. Originally, Riven was a skirmisher who was meant to be able to fight multiple melee enemies, and previously excelled at split pushing against most other Top Lane champions. These days, Riven struggles against the majority of the champion pool 1v1. Split pushing is worthless now with the empowered re-call on baron. Not to mention if your team loses a fight while you are split pushing, the game usually becomes unmanageable, as Riven is reduced to a Flash stun bot with not much other usage when behind and forced to group with her team. This same thing can be said about many other Top lane champions inside the current Season 8 meta. Due to this, winning lane means you almost are required to give up lane as a Top lane and roam around to help your team. Long gone are the days of bringing the enemy team to you.
The struggle of a roaming laner is even more real. There are so many times where I ping, type in the chat, and clearly communicate to my team when I'm trying to make a nice roam towards their lane. The fact is however, a lot of players don't want to play with you. Many times when I make an attempt to help my teammates it backfires because they simply do not want to participate or don't want me to come down to their lane. This often leads to deaths, lost gold being away from lane that can't be made up, and levels lost that can't be easily regained. Even with the best communication in the world, there's nothing you can accomplish when the other players on your team do not want to work with you.
As bad as they seemed back in the day, I really wish Riot would bring back many of the things that seemed to dissuade team play. Things like aura's on items, self buffs on champions, point and click abilities. I'm sure many of you would disagree, but just stop and think for a minute -- Would you rather know being the better player that you have the tools at your disposal to attempt carrying, or would you rather cross your fingers and pray that the Galio on your team understands how to roam and is willing to use his ultimate on you?
The fact is, not everyone cares about you and you don't care about everyone out there either. We're all playing with other players that we've never met before and there is no way of knowing if you can trust that your team will be there. Teamwork is the biggest flaw and frustration for both Seasons 7 and 8. It's always been present to an extent, but the past two Seasons have been where Riot has enforced and drilled the nails into the coffin the most. These changes are NOT positive, despite what everyone is brain washed to believe, and are why amazing players like Faker are struggling more than ever in League of Legends.
Sometimes teamwork is a good thing, however forced teamwork is never a good thing.