What you are describing is an entity-attribute-value model (EAV). It is a very poor way to design a data model.
Although the data model is quite flexible, querying such a data model is quite complicated. You frequently end up having to self-join a table n times if you want to select or filter on n different attributes. That gets slow rather slow and becomes rather hard to optimize relatively quickly.
Plus, you generally end up building a lot of functionality that the database or your ORM would provide.