I think this is an argument of Technicians vs Engineers,
Techs will tell you what can/can't be done with regard to pre-defined operating limits set by either the manufacturer or governing body. They're understanding of the exact makeup and physics of the machine is not complete, but more than adequate to perform maintenance/operational tasks and send qualified analysis of performance back to the manufacturer or operator. They can probably perform these tasks better than the engineer that created them.
An engineer will tell you a theory of what can be achieved given analysis, data and creativity (ingenuity). This is then put into limited testing and proved possible and eventually incorporated into everyday use. An engineer does not say no, but may possibly say not yet.
The gas turbine is a good example, it is not a modern concept and actually has basic patents that predate the the piston internal combustion engine. The first powerful turbine engines were fitted to ships in the late 1800s (low powered ones having been used in early 1800s), being steam fired these were not suitable for aircraft. A number of technically minded people worked on turbines throughout the early 1900s for aircraft application, but were unsuccessful, some physicists even said not possible. It was through the combined efforts of a number of engineers designing and patenting various componants that eventually made it possible to create a jet engine.
I don't think there is any doubt that even these "old" technology pistons can be run LOP and safely. It may require more than the standard guages for the average pilot to operate without long term damage but it is possible, but this is possibly true of any leaning, not just LOP.
Having a closed mind and just saying no, is definitly not the attribute of an engineer. An engineer would not dismiss data without looking at it first. In-flight operational data from most piston engine trends is very poor, both in the instrumentation it is gained from to the poor recording of the data by the pilots. Saying that engines have been damaged from being run LOP can not be quantified from a few burnt cylinders and valves as its well know this could be caused by a number of factors. It is very hard to establish whether the pilots were actually operating LOP or not if they themselves don't know how to do it correctly. It is a speculative appraisal which needs to be analysed at a metalurgical level, and possible testing carried out to extract the exact nature of the failure, even this may not possibly come up with an answer without knowing exactly what happened at what setting.
What an engineer would do is to run the engine in a controlled experiment, collect data on the internal runnings, temps, pressures etc. Compare this to the materials, construction of the unit and come up with whether it is more damaging one way or another. This data could then be put into practice and measure the outcomes of operational use from trends and condition monitoring.