In a strong economy, all amenities (golf, tennis, weddings, dining, etc) can be successful under one roof But, in a weak economy, some, or all, of the parts can fail. Having said that, a place like Wal-Mart is (much to my dismay) an example of quite lucrative operation that at least pretends to offer everything to everyone at one location. But then again, they also don't pretend to have any real variation from location to location. It is their monotony that aids in their success.
But, really, there are at least a couple of different questions being asked here: First is whether the actual design of a golf course suffers from the presence of wedding amenities. By itself, no, I don't think it necessarily does. However, if one goes with the maxim that a "championship" course, or a club that is "golf only," is designed with different intentions and geared towards different playing abilities than a "members" course or "country club," then yes, the architect will make concessions that could conceivably dumb down the playing characteristics. But, then again, a designer also has the option to refuse the project in the first place, perhaps leaving the job to a less skilled practitioner who may create something that is undesirable to play anyway and thus destined to fail on its own accord, or perhaps another strong designer would take the job, create something wonderful, and the golf is successful, in spite of the weddings.
Second is whether wedding facilities at golf courses divert monies away from the golf course, including both it's design and maintenance budget. This unquestionably happens, but this might just be a the scapegoat taking the blame for other poor decisions. Consider Riviera Country Club in Pacific Palisades, CA. They have top notch dining facilities, a hotel, a well-used tennis club, and play host to a myriad of weddings and receptions in their over-the-top, exorbitantly expensive clubhouse. They also have an above average, to great, golf course. Yet they are not collapsing, and I would think that they are not the exception that proves the rule; there are many others out there. Granted that they probably derive some form of income by hosting an annual PGA Tour event, but more than this, they know their clientele. They are located in one of the wealthiest areas of America and sell themselves to that crowd. Conversely, when a developer in a part of the world with less resources tries the same thing, the chance for success decreases, almost exponentially. It is not the weddings, or the tennis, or the golf by themselves, but possibly just uninformed, or misinformed decisions on the part of a developer who didn't finish his homework.
Rather than assuming that weddings were bringing the place down and that a "golf only" facility would have been successful, it is equally as likely that NOTHING had a chance for success at that time and at that place.