Would you like to substantiate that claim?
How? Isn't this thread enough? lol
Well, in my own personal experience I had 9 clients (they didn't know each other, nor did I setup their stuff for them) including myself using Godaddy for hosting/DNS/email etc
It became such an issue of uptime that eventually they asked me to move them. In a span of 6 months I had these 9 people complain to me.
If you want some more evidence, just use our good ol' friend google.
When I go to a steak house I don't get the fish. Thus
If I use an ISP for internet access (which they specialize in), I don't use their hosting or take up any free domain/dns/email offers. I have them to provide me internet, that's it. It leaves me mobile enough to dump their asses and move onto another ISP without batting an eye. Because I use what they specialize in.
If I want hosting, I go to someone who specialize in hosting and not just provide it as one of the services they provide as well. I don't use their DNS servers, because it's quite likely they don't have a proper setup for fallover when it comes to DNS servers, and it's also a bitch to move your DNS every single time you change a host. So I have separate independently maintained DNS servers (either through Rackspace or Cloudflare). That means if my host is ****ing me around, I just moved to another host. I think it took me a total of 10 minutes to move from one host to another on Friday night (including the few beers I had and surfing random stuff) and the effect was immediate, no 24 hour waiting period or downtime at all.
If I want email, I go to someone who does email. It's separate from my hosting because hosting a website and hosting email is quite different. I don't have any issues with my email being down or unavailable or scared to move hosting because I need to then move emails. It also affords me better spam protection and tools available for EMAIL.
Separating these services (and you might think it's expensive, it's not, maybe costs me R120 for my entire setup each month and I host a few dozen sites with email) pays off in the long run.
If I look at my stats for the last 5 years, I've had 5 nines uptime ON AVERAGE while I'm agile to change when I please without headaches and woes.