...you do realise this is pure Nirvana fallacy right? "If you can't do something about the impossibly large big picture you shouldn't do such small things you're capable of either" which is bullshit reasoning and basically just an excuse to do nothing.
Sometimes kindness is the greatest cruelty: by habitually feeding strays, you only teach them to depend on humans, allowing their hunting and foraging skills to wither and leaving them in the lurch should the kindness run out. An occasional act of charity is one thing, but anything more than that requires thinking about the consequences of your actions.
Unfortunately, this is a real problem with the world today: so many people push for things that seem good on the surface, but are sometimes even just one step removed from a reality of being worse than doing nothing.