It's completely reasonable to want potential employees who are likely to stay at your company for more than a year. If someone's entire experience is leaving places after less than a year, either they are bad employees who are fired or quit due to performance issues, or they never intend to stick around long anywhere.

For some kinds of work, that's fine, but I think most companies of all kinds would prefer employees who will stay with them for at least a year.

It's totally valid for someone to want to hop companies and favor that lifestyle. But it's also valid for companies to favor people who don't want to hop.