Last bit is not true. Lots of control but there is aways a limit. Good designers and developers do as much as possible and build things so that they come out consistently on the website. We give clients control but we also make sure they can not screw up a site lots. If related pages come out differently then we have done a bad job and we go as far as limiting the WYSIWYG to solve that.
Any client who has moaned and pestered for more control has thus broke their site and then come moaning after. They do not go "we messed it up, can you help us please" , its their fault and they blame you quite often.
But yeah, there is a point where if they want things done and its a template change for example you as a developer need to be doing it. Content - Yes, they can, but not everything.
This.
In my work our clients generally have far too much control because our CMS is so powerful even with most of the modules switched off, you have to set boundaries and usually even take is so far as to simplify the admin system for clients you know will not be capable of using certain features. The number of times we have had a support request that has cost me development time on another site because a client has done something stupid or made a hash of their site is uncountable. We charge per hour for my time when someone does this.
There are also many occasions where a client will want something a bit more bespoke than CMS functionality will provide such as installation of a jQuery based carousel or gallery, or a piece of flash, or configuration of Google Analytics, etc. All these are extras that potentially need to be charged for to install on someones website that a CMS may not cover.
Unfortunately most clients are not computer experts, let alone webmasters. Expecting anything from them beyond the ability to use TinyMCE or another WYSIWYG editor for adding content can be dangerous.