@Canadavisa92
Not necessarily true. I'm in HR and have written several employment letters for my employees - that they have used for their PR. All of them were approved. IRCC finds it easy if you take key words listed on the CIC website and write down the roles and responsibilities.
Employment letters have to be:
Transcribed in English (If provided in another language) and must be on a company letterhead: with job title, start date, end date (or if currently employed), roles & responsibilities, NOC code, FT/PT (with number of hours per week, if possible), and contact info for the signing authority. Lastly, it has to be signed and dated by the issuer. If all this is there, you're golden.