This is not true!! Don't let the doom and gloom get to you.
Firms take holistic approaches to applications, sure there may be some firms who put a stronger emphasis on grades but many firms do not. I secured a TC at a top US firm without ever even getting a first in any module and only one vac scheme before. One example doesn't exemplify the whole industry, I know the application cycle can feel rough but quality applications are worth it- at the firm I got my TC I spent ages researching them and was truly interested by the work they were doing, and it shone through and made a difference.
Quality applications and a genuine interest in the firm do actually make a difference, despite how hard that might be to believe because of how alienating the process feels.
I appreciate the sentiment within your message. But my thought process isn't based on a single person's success. It's a view which I've developed across multiple application cycles (after seeing who makes it, and who doesn't).
I'd say that around 40-45% of my LLB cohort landed a role in commercial law prior to (or immediately after) graduating from university. In stark contrast, I've also seen some very bright people return to their home countries because they were unable to land a TC. And, these people didn't return home because they were incapable of becoming a commercial solicitor – they were effectively forced to return because they couldn't impress graduate recruitment.
This application cycle, I've written some of my best applications ever. I have only applied to firms which specialise (or have strengths) in the areas of law I am passionate about. I've had my applications reviewed by future/current trainees at the firms I've applied to. Their feedback has been very positive. These applications have been tailored, specific to the firm, and have demonstrated my knowledge/interest/experiences. Yet, for the vast majority of applications I've made, I haven't even been invited to a second stage.
The simple fact is that, while my grades are decent, my experiences aren't that impressive. You had a vac scheme before you secured a TC at a top US firm. My experience is limited to open days and the subjects I studied at university. I promise you, no matter how hard I try to spin the experiences I have, I won't be as successful as you without a great deal of luck.