Hey jus my 2 cents, never had a lesson my self so I don't know what goes on in 'em but I'm pretty sure they jus teach you how to physically play an instrument(your voice being one too) I think the need to write songs is purely a personal perspective e.g. Music only exists because people have emotional reactions to harmonized sound also since language is incorporated so dominantly into our being lyrics have the same effect. Musicians over the years have found paths through chords and notes to find sounds that sound good and feel good,if you wanna make good music you should listen to music, find a sound you respond to(figuring out why should give you some good lyrics too) also if you play for yourself you'll naturally end up playing for others seeing as though we're basically identical to every one at some point inside, bare minimum being 1:mortality.
Anyway if you've ever walked into a wall face first 100 times over you'll realize,with anything-not asking for help:BAD IDEA.
So I guess in short:
Teaching yourself:Bad
Playing for yourself:Good