In the web hosting world, we're probably talking mostly about email.
When it comes to email interfaces - and if you side step privacy concerns - I don't think there's anything better than Gmail. It has a nice, easy to use interface (I haven't tried their new interface yet). It's easy to organize. And it's easy to search for old messages - try doing that on a typical cPanel server with gigs of messages.
Being able to host your domain name's email inside a Google interface would certainly be appealing. And in fact, at one time, it was. Google used to offer Google for your domain name for free, with unlimited (or at least a very large number) of email users. Then Google found out they could monetize this, which I'm not necessarily blaming them. But the $5/mo per email user seems quite high. Although, it obviously seems to be working for them because they haven't lowered the price.
I'd say the majority of our clients have about 10 email accounts on their domain name. Well, at $5 a pop per user, that's an extra $50/mo our clients would be paying every month for email. I don't see that as feasible.
Zoho on the other hand is almost an exact duplicate of the Gmail interface - it even has an Android App (Apple too? Sorry, I don't use Apple). And it allows up to 25 email users for free, albeit each with a 5GB quota.
Now, you definitely don't have as much control of your email when using Zoho (or Gsuites for that matter). If piping mail content through a script is important to you, then you don't want to use Zoho or Gsuites - but I suspect the vast majority of users have no idea what I'm talking about with that. Most users just want a clean interface that they can check their email from, and ideally a phone app to be able to check mail on the go. And for that, unless the 5GB quota limit is an issue for you, I find it hard not to recommend Zoho over Gsuites. In fact, I'm really surprised that I don't see Zoho mentioned more.
Of course, if Zoho becomes a popular email alternative, then it might spur changes to Zoho's pricing model. I suspect that that is what happened with Gsuites. So keep that in mind.