Earlier quoted context omitted.
You can create and use as many addresses as you want - there's absolutely no reason to keep your savings on the same address as the tip jar.
Yes but everyone can see how much you received over the years. And, well, if there have been thousands of BTC passed through that tip jar, it's reasonable to assume that the organization still has control over a big amount of these funds.
Only if you use static addresses. If you're receiving thousands of BTCs, you can easily afford to write a widget that generates a new address for each donor (behind a captcha, to avoid DoS).