Why did they have six jobs before thirty? Who knows? May be they switched career orientation (I've started in operations and moved into software development, that required a "hop"), may be they didn't know what they were looking for, may be they had a family situation.
Likely, if they worked at a single company for ten years, that's irrelevant if they manage to have the desired level of competence and have the desired level of passion and curiosity.
Are they leaving companies since they were fired (rather than downsized or left voluntarily) or put on a performance plan? That's to be checked through their references. Are they hopping purely for increased compensation? Then just refuse to meet outlandish salary demands (out of proportion to their skill level).
It's true that a bad looking resume may not make it past an HR filter. However, I've been swamped by recruiters (agency and company HR) at all times even after my resume had shown I've only been a few months at my company. Furthermore, when you're over thirty you'll likely have a network of coworkers who will be able to refer you to jobs bypassing the HR filter.
Rather than worry about what a blogger thinks about you and your generation, worry about learning and increasing your competence level. Make multiple companies fight over you (because you have a rare talent and excel at it) instead of fighting to get into a company.