If this were true then there would be no adsense sites with these keywords and just how would those lawyers spend their money with adsense then?
I don't think you ned to be an insurance agent or related field to set up an insurance site and so forth. It is important however for a sight to stick to its "niche" an insurance or money site should have content related to it, a gardening site the same and so on. Wi the right content Google will be able to place the right ads to the page and people interested on the site or page's subject has high probability to click on the ads. IMHO
it's true google started this new system last year, also a few months a ago i think december, they seem to detect duplicate content, they don't approve sites and new accounts, that has copies on the internet, it's like copyscape the system detects these. so if you make a new account using blogspot or your new site don't copy content from other sites. it's true whats Posts721 says, they really ban you if you target keywords, not now, not tomorrow, but your time will come as google monitors millions of pages and sites, don't get your site in the waiting list it will come.