Functions like findPackage() or go() require a search index. This search index can either be created on-the-fly or be provided as a separate argument. In the latter case a search index can be built using buildIndex(). This index can include download figures for the packages
(this feature is turned on with download.stats = TRUE). Including download stats requires significant time (may well be > 1 hour) for the index to be built. Therefore, when findPackage() is called without
providing an index, the index that is created on-the-fly does not contain CRAN download figures.