Although i understand where the concern comes from (massive gold = faster purchases), I have yet to see Kleptomancy offer a better (or worse) advantage than other primary keystones like Electrocute, Phase Rush, Aery, or Aftershock when applied.
Like with most abilities in league that have gravity towards an advantage, it has counterplay: Klepto is not a speed boost, damage boost, or defense by itself, so it is prone to those abilities that are. It's also prone to people who have cc, kind of like a Draven is: Gangplank and Ez's counterplay is basically to ambush them, or isolate them from using their abilities.
Maybe I'm biased, but Evelynn counters both GP and Ezreal right now, because her Sorcery AP scaling is huge, along with movement speeds. She roughly has 40% more AP now than she did in Season 7 by 15-20 minutes, so she can actually get her executes during a charm much much more reliably. And, neither GP or Ez can get away. I can also counter them with a Leona, a Karma, etc. Learn ways to cc these guys and coordinate with your team to take them out. Stop fighting them out in the open, at long range or in chase. Learn to see what they don't, the angles that will allow you to reach them, and take them out first in fights.
I mean.... this is just another pre nerf Draven argument, or a post buff Nasus argument: Pre nerf Draven = 1kill changes the game and snowballs him, because that 1 kill gave him 700+ Gold. Post Buff Nasus = Can kill anyone in close quarters because of the 50% CDR reduction on Siphoning during his ult, and can use ult to stack much faster. They become raid bosses. Riot loves having a raid boss here or there, because it affects team decision making.
Gold aside, I don't see it as a "must play this way or lose" scenario. It might be annoying, but there are builds out there that do more damage, more reliably, survive more often, and shut down these guys that have 4k more gold than you.