Obviously, like most professions, there are bad and lazy ones out there; but a great EA is easily worth their fee.
Even if you're happy to write the particulars, take the photos, upload them to Rightmove (assuming they accept an ad from an individual), pay for Rightmove, deal with all of the emails and phone calls at all times of the day M-F 9-5, and show people around yourself...
You will find it extremely awkward to ask people for proof that they are ready to proceed and have the funds - and be insistent when they try to lie or swerve telling you about their true circumstances.
Potential buyers will try to offer you less, purely because there's no EA middleman; and they will have their eyes on the amount that you're saving by not paying a cut to the EA when they negotiate the price with you: they will expect their 'share' of that saving, so you might only save half as much as you anticipated. They will also likely massively overplay the 'huge' savings that you're making with no EA.
The EA will know the local timewasters, chancers and trouble-causers very well. Have you really saved anything if you end up waiting 6 months for your 'buyer' to resolve this issue and that issue and the other issue, when they know all along that they're playing the long game and aren't serious/able to proceed - either at all or without 'suddenly finding' that they can only go ahead by knocking a huge amount off the price they pay you, so you either take a huge hit or lose the house you're buying. These people can be very persuasive indeed when stringing you along, knowing that individuals will be far more likely to browbeat and overcome than a professional intermediary.
I'm obviously not suggesting that this will always happen, but when we were selling a deceased family member's house, the EA called us 'off the record'. It turned out that a local dodgy bloke had approached them with a remarkably good offer - as he usually did for each new house they listed - and tried to offer them a bribe to 'persuade' us to go with him. Apparently, his usual MO would be to pretend he was the buyer, but then the actual buyer would end up being somebody completely different. Also, he would come in with the best offer, fully intending to pay far, far less once he had his foot in the door.
Once, he'd gone to the EA's office and physically held him up against a wall, with his hand around his throat - in his determination to get a house for a song - and the police had to be called. Our EA - who was very friendly, professional, helpful and honest throughout (even when it would have been more profitable for him to have lied) - spoke to us (he wouldn't put it in an email for fear of potential repercussions) to say that, although they legally had to pass on all offers and that his was the best, just do not go with him, whatever we did.
Of course, then it became his problem to have to explain to this unpleasant, angry man that we had not accepted his offer - and to fend him off when he demanded to know what offer he had to make (clearly never intending to actually pay anything like it) in order to secure the house. If we had swerved the EA and advertised it ourselves, we would have gone with him, completely oblivious, and ended up with a huge amount of delay, heartbreak, awkwardness and possibly even threats and violence.
Personally, I wouldn't ask the question "Why don't I just sell it myself?"; rather I'd spend time to research the options, ask around (somebody did just that the other day on MN) and ask "WHICH EA shall I use?".