We recommend implementing a PIM system if you have a product catalog of 15,000 or more products.
With some solutions, you can easily load content from your ERP system into your web store without requiring a PIM system. For example, with Sana Commerce you can upload additional product information, a short movie or several pictures directly from your ERP to your web store.
You can do this for every product in your database — but if you have an incredibly extensive (15,000+) catalog, you might want some help from a PIM system.