Is it true that accounting firms don't hire without prior experience?
That's a horribly wrong statement! Where do they expect people to get experience from if they only hire experienced people? All the large accounting firms hire many entry level accountants each fall. Many of those had a prior internship there so if you can first get an internship there (or even elsewhere) you have a better shot. It's definitely much harder to get an entry level job than it is once you have experience.
To say that they don't hire is just untrue!! They hire tons of people, it just may be hard to get one of the spots with the many applicants.
Keep in mind that the hiring at large firms for entry level is done once a year in the fall for the coming fall whereas experienced hires are usually needed throughout the year (or on an as needed basis).