Generally, frowned upon (to use swivel in the ground tackle) - it (usually) reduces the safe working load of the rode.
In general, ground tackle is a pretty hotly debated topic among sailors, with many people having strong opinions that don't always agree. Choice of anchor is something that few seem able to agree upon. On some web forums, the debates over them gets pretty heated. I guess that I should not be surprised to encounter opinions on swivels that contradict mine as well. The cordial nature of that discussion here is a welcomed change from other forums.
To date, most of the people I have met that don't like swivels, were people who were not aware of how to use them correctly or were on boats with anchors that got pulled up by hand. If your reasons for not liking them are something other than this, please help me to understand the shortcomings that I am unaware of.
Around here swivels are pretty popular on bigger boats. I have also seen them on the pulpit of a brand new multi-million dollar yacht at the factory. Most every mooring I see around here has at least one swivel.
There are many different swivels out there. The cheap ones are certainly to be frowned upon, but the better quality ones have a pretty good track record when properly installed & occasionally inspected for degradation. Most of the failures that I have seen have either been from improper use or corrosion after long term use. Both of these issues are avoidable. Below is an example of improper installation & the resulting failure from a side load during a tide change. This failure could have been avoided with the addition of a few links of chain between the swivel & the anchor.