leaflet and open layers have different use-cases. This is a massive oversimplification, but roughly, one way of thinking of it is that leaflet is more suited t

leaflet and open layers have different use-cases. This is a massive oversimplification, but roughly, one way of thinking of it is that leaflet is more suited to consumer-facing web maps and openlayers is more appropriate for heavy gis workloads; e.g. a web app for visualising business locations worldwide vs a web app for manipulating SHP data and EPSG projections. That's not to say Leaflet can't be used for the latter -- e.g. in combination with some other tools like turf -- but OL is being developed with this kind of stuff on mind.