Valentine's aftermath tends to bring into contrast the conflict between hope and experience. For affairs of the heart, hope's triumph may be necessary--after all, every relationship you are in will fail, up until one doesn't. For affairs of the pen, experience may be a better guide. I have writing friends, authors with smarts and talent, who hope that writing well and telling a good story will be 'enough' somehow. 'Enough' may be ill-defined, but usually means earning sufficient money from writing to at least contemplate quitting a day job. The hard lessons of experience teach that talent and skill are rarely 'enough' by themselves.
In a shallow fashion, simply writing well without attempting much in the way of publishing can accomplish little more than posthumous success, at best. To make a living out of writing, you at least have to send your excellent work off to a publisher or an agent or a journal (more likely, many publishers, agents, and journals). I am pretty sure that even the straw man standing in for my friends in this argument would allow that of course you have to submit your work for publication somewhere, and possibly even many somewheres, and that this is me putting words in his strawy mouth--it's just all this blogging and tweeting and self-promotion that isn't really necessary.
I'm not particularly well suited to personally speak to finding writing success through self-promotion. Sure, I have hawked a book containing my work pretty hard at times, and I still think you should definitely go out and buy as many copies of it as your Kindle will hold, but so far I am not particularly close to ready to give up my day job. From looking around me, though, I know that talent and hard work isn't enough to get a start in most other industries, so why should writing be any different?
Restaurants put up signs and buy advertising to let diners know they are there. Attorneys starting their own firm will hand out business cards to anyone who holds still. Newly licensed doctors usually join an established medical practice (which necessarily involves a bit of self-promotion to get the job in the first place), but if they want to go out on their own you can bet they'll take out an ad in the yellow pages. If you are starting a new business, you have to let people know you are there, and that's true whether you are making art or setting broken bones.
I am pretty much an unknown writer. I am lucky enough to have aggregated together a few thousand readers of something of mine, through tweeting and blogging and publishing as part of an anthology with better writers than me. I am still very much a new scribbler on the block, though, so I will carry on with the self-promotion.