Feature summary (what you would like to be able to do and where):

Users should not be able to add statements that result in constraint violations and be offered an explanation why.

Use case(s) (list the steps that you performed to discover that problem, and describe the actual underlying problem which you want to solve. Do not describe only a solution):

Newcomers or self-promoters come to Wikidata and make items that violate 5+ constraints and do not take any action fixing them, leaving it others to do so. It's very likely that these high-constraint-violation items are being created at a rate much faster than they are being fixed. This is resulting in a worse average data quality across Wikidata.

Here's an example of a terrible item:

• https://www.wikidata.org/w/index.php?title=Q116811692&oldid=1835970604

Because of this fact and that fixing them is a very annoying task for experienced editor to do, I'm proposing that a system be developed that accomplishes this proposal and is implemented on Wikidata.

Benefits (why should this be implemented?):

Better average data quality.
Action to adjust constraints when needed becomes more-frequent.