So, if most logons freeze up after 3 or 4 fails,....

[AG31]

...how can hackers break into a site by trying hundreds/thousands of possibilities?

 

[drusus]

...how can hackers break into a site by trying hundreds/thousands of possibilities?

There's a lot more to hacking than brute force password cracks. Much of it involves exploiting vulnerabilities in databases or intercepting information as it passes back & forth. The most vulnerable part of a network is often the people using it, putting passwords in open files or downloading virus ridden programs from email or websites.

Hacking and ramsomware is a massive industry and there's a constant arms race between software companies and criminals who try to exploit them.