Freestanding sleeves have one very large advantage: they stay round either with temp changes or pressure changes. Closed deck motors always distort under both conditions, plus under cylinder head bolting loads. Thus, engine builders will resort to "hot" honing, using torqued in place deck plates when boring and honing, larger piston to cylinder wall clearances, and ring designs that are more tolerant of out of round bores. The top 15% of the cylinder undergoes the most heat and pressure changes during use. So, if a sleeve doesn't hold up under use, make them with thicker walls near the top. Additionally, how and where the head is bolted to the block affects the clamping load between deck or sleeve and head mating surfaces.
Another over-looked issue is cooling. Uniformity of cooling efficacy around the entire sleeve and from one end of the motor to the other is almost never achieved. Pumping coolant into a block at one end, metering its flow from block to head via hole sizes in the head gasket, and dumping it out the other end, is about equal in technological sophistication to Fred Flintstone's vehicle drive system.
Modern head gaskets can use self-energizing seal rings, copper rings, or other technologies to seal those mating surfaces. If a good head gasket won't maintain a seal on a sleeve, it is most likely a bolt/stud problem, a design issue with their location and/or quantity, or the rigidity of the block or head that is the root cause of the failures.
All vehicle manufacturers have cost/benefit issues to consider and manufacturing constraints. So, we get compromises best suited to intended use and profitability.