Your logo is you or your business' first point of contact with the outside world. If people connect with your branding, the likelihood is that they will open up to whatever it is offering them. Great logo design requires a complex mixture of design skills, creative theory, and skillful application.
Of course, logo design is just one small subset of branding, but the logo or brand mark remains the centrepiece of most branding schemes.
A logo design app or website is not going to create a branding masterpiece – but you know this. Some people are simply looking for a quick, cheap logo that reflects their start-up brand until it has expanded enough to merit a full brand identity created by a professional designer or agency.