We have encouraged folks to include .stp files with their .stl(s) both in posts in threads and in the *Best Practices* .doc which is in the Repository along side the Catalog. There are 98 .stp files in the Repository with their associated .stl(s). We certainly haven't deleted or discouraged anyone from providing STEP files.
Please!!! By all means, provide STEP(s) with your .STL(s)... they are Welcomed and Encouraged!!!
The easier that we can make this for the end user... especially for the beginner ...the better. We are all teachers. The best we can do for our hobby is share our experiences and knowledge.
STEP/.stp: STEP is a file extension for a 3-D graphic file used by CAD software. STP stands for Standard for the Exchange of Product model data. STP files are used to store 3D image data in an ASCII format, following the standards defined in ISO 10303-21 : Clear Text Encoding of the Exchange Structure.