I was deeply involved with an ultralight club and I was a Commercial Instrument Pilot when the Sport Rules were adopted.
I was also the owner at the time of a 325# single seat "ultralight-type" airplane, more commonly called a FAT ultralight.
I can answer the OP's question without ambiguity.
There's two distinct chapters of the Sport Pilot implementation.
1) The INTENTION of the rule
2) The actual result of the rule.
These are the goals of the rule as it was intended.
* Stop people, many of which had never had ANY training from flying around in heavy, non-Part 103-compliant ultralights, some with 2 seats and passengers.
* Encourage all ultralight pilots to get some training and increase safety.
* Invigorate entry-level aviation to help the future pilot shortage that was looming.
* Allow fat ultralight pilots to log their time toward higher ratings.
* Provide a cheaper way for owners to maintain an aircraft they own.
* Stimulate manufacturing of new, modern, cheap aircraft by allowing their manufacture under much cheaper certification.
* Enable a new aviator to share their experience with a single passenger very soon and with a lot less cash paid out.
* Provide for CFI's and a cheaper path for Primary students to get a rating/license that could later be upgraded to Private.
The unintended consequences were:
* A lot of slick, fast, expensive airplanes that no-one want or can afford that are rarely available for rent at the local FBO, to train in.
* A useless group of flight instructors, students, and pilots whose instruction of flight time could not be used for higher ratings.
* Made getting a pilots license of any flavor MORE expensive, not less.
* Fostered building a "wall" between "real pilots" (Private and Above) and "pretend pilots" (Sport Pilots).
Most recently, due to Basic Med and now allowing Sport CFI instruction to be used for higher ratings, the FAA has blended Sport Pilots
with Private Pilots and above. There's really no reason now to not get a Private License because you no longer need a medical and certified aircraft are no more expensive to rent than an LSA.
Sport Pilot CFI
Commercial Rotorcraft Helicopter
Manufacturing Engineer II, Meggitt Airframe Systems, Fuel Systems & Composites Group