If those collections are digitized, they’re in GBIF and can used on iNat if on map you check on filter for GBIF, so you can revisit sites and look what is there now (though old collections suffer from vague place descriptions). But yes, most people don’t need to collect and I can get 90%+ of plants ided to species without any specimens, and other percentage is either my fault of not getting specific shots or just it being the wrong time of the year, you can photograph pretty much everything but roots without disturbing the whole plant.