It is essential to clarify some misconceptions in your question. First, the Prophet Muhammad (peace be upon him) did not have 13 wives. He had multiple marriages, but the actual number of wives was 11, not 13. Among these marriages, most were contracted for various reasons, such as forming alliances, establishing social bonds, and caring for widows.
Regarding the practice of polygamy in Islam, it is true that Islam allows men to have up to four wives under specific conditions, as mentioned in the Quran (Surah An-Nisa 4:3). However, it is crucial to understand the context and restrictions surrounding this practice. Polygamy in Islam is not obligatory or encouraged; rather, it is viewed as an exception and permitted under certain conditions, such as ensuring fair treatment and support for all wives.
In many Muslim-majority countries today, polygamy is not a common practice, and the majority of Muslim men have only one wife. The prevalence of polygamy varies significantly from one region to another and is influenced by cultural, legal, and social factors more than religious reasons.
Regarding the issue of older Muslim men marrying teenage girls, this is not a practice specifically encouraged or justified by the Prophet Muhammad's example. Again, such practices are often influenced by cultural norms and local customs rather than religious teachings.
Islam, like other major religions, should not be judged solely based on the actions of certain individuals throughout history or in specific cultural contexts. The way Muslims understand and practice their faith can vary widely depending on their interpretation of religious texts and the influence of local customs and traditions.
It's crucial to approach any religion with an open mind and seek to understand its teachings from reputable sources, considering historical context and the broader principles of the faith rather than focusing on isolated incidents or individual actions.