It's true that managers have a lot of latitude to read self summaries and either amplify or disregard them. The #1 thing you can do to avoid problems with your own reviews is to actually understand what your manager's and the company's priorities are and align your work to them. I have given poor reviews to people who invested lots of time and energy in projects and probably even did good work on them, because they were _completely_ off strategy and completed before anyone who knew better could tell them they were a waste of time and energy.
This isn't malevolent. It's because every manager is tasked with supporting the company's overall goals, frequently with very limited resources. Work that veers off into left field, even when perceived as valuable from the employee's or peer's perspective, is basically lost opportunity to do something more valuable. And that gets very expensive when trying to grow quickly.
If you want to get ahead, you and your manager need to work together to make sure the work delivers results, is aligned with strategy, is timely, and is visible to other managers and execs. Hit all four, and the need for recognition is obvious. I've seen execs argue against managers that individuals deserve promotion. Miss one, and you're probably relying on your manager's good will and clout to make the case.
If the work is not aligned with strategy or didn't deliver results but took a lot of time, your manager will look like a fool arguing that you deserve recognition for it.
Also, re: exceeding expectations, this comes up in every org and with every team. Everyone is always graded on a curve, both within your individual team and across each exec's organization. This is because the budget for compensation is fixed ahead of time based on assumptions about the percentage of employees that will exceed expectations. As long as each exec gets roughly the expected number of employees exceeding and meeting expectations, their recommendations for promotions, bonuses, and comp adjustments will likely be approved.
If the ratio for a given exec is out of whack, the only options are: 1) Get it back in line, 2) Take budget from someone else, or 3) Increase the compensation budget.
(3) frequently can't be done without board approval, so is not really an option. (2) is going to start a knife fight between execs over whose employees deserve it more, which nobody wants. This leaves (1). This is why alignment and upward and outward visibility is so important - it banks you social capital with the people who have to allocate limited resources.