Yourself and Myself, now this is interesting. Many languages, (and English a time ago), have different ways of addressing people. Like in French where you say 'vous' to an adult of similar of higher status, but 'tu' to a child or possibly a servant.
When these youngsters in call centres for example address you on the phone, saying 'you' sounds too forward, so they use the modified 'yourself' to show they are of lower status. Ditto with 'me' or 'I' It sounds too strong to say 'it was said by me' so it becomes 'it was said by myself'. I don't think this one will go away 