They made the same with local Czech eBay-like website https://www.aukro.cz/ . Previously it was a fast website. Transition to the webapp was painful, their filtering component was not working properly on mobile. It still takes several seconds until the initial white page switches to the rendered DOM. They lost many customers due to this painful transition. I think they fixed some of the problems (I know filtering component works ok now) but I basically stopped using it since that transition too.