in dota 2 you can do that. The issue is league client is not connected with the game. They could add so many features like this if they just followed the dota 2 model. The issue with that would be slight increase in hardware requirement for the users.
But I still think it's a fair cost, its 2018 and if you cant run a game like dota 2, then you really need to upgrade your system. And it's not even that high of an upgrade.
OS: Windows 7.
Processor: Dual core from Intel or AMD at 2.8 GHz.
Memory: 4 GB RAM.
Graphics: nVidia GeForce 8600/9600GT, ATI/AMD Radeon HD2600/3600.
DirectX: Version 9.0c.
Network: Broadband Internet connection.
Hard Drive: 8 GB available space.
Sound Card: DirectX Compatible.
Is reasonable thing to ask. I mean why let so many people suffer and prevent them from having these QoL changes, just because some people can not afford a cheap computer. I mean how much the above stated specs would cost 60- 100 $ for a second hand computer/laptop? Sure for some that would be quite a high lump sum price. But may be if you save it up over the period of months/ a year, it's not a too much to ask is it?