The dating systems of ad and bc have been commonly used to refer to historical events for centuries. The ad system refers to the period after the birth of Jesus Christ, while the bc system refers to the period before his birth. However, these dating systems are no longer the preferred method of dating historical events for a number of reasons.

One of the main reasons why ad and bc are no longer used is because of their religious connotations. The ad system was first introduced in the sixth century by the monk Dionysius Exiguus in an effort to establish a more accurate method of calculating the date of Easter. Later, the use of ad to mark the years after the birth of Jesus Christ was popularized by the Venerable Bede in the eighth century. However, these systems are now considered inappropriate for secular use because they are based on the Christian belief that Jesus Christ was the son of God and the savior of humanity. This can be seen as promoting a particular religious view, which is not appropriate in a secular context.
In addition to their religious connotations, ad and bc are also not precise enough for modern historical dating. The ad system assumes that Jesus Christ was born in the year 1, which is now known to be incorrect. Historians now believe that Jesus was born sometime between 6 and 4 BC, which means that the ad system is off by a few years. While this may not seem like a significant difference, it can have a significant impact when it comes to dating historical events.
Furthermore, ad and bc are also considered Eurocentric. This is because they are based on the Christian calendar, which was developed in Europe and reflects European cultural and religious values. This means that ad and bc do not reflect the diversity of human history and can be seen as promoting a Western-centric view of the world.
As a result of these issues, alternative dating systems have emerged in recent years. One of the most popular of these is the Common Era (CE) system, which is now widely used in academic and secular contexts. The CE system is similar to ad in that it marks the years after the birth of Jesus Christ, but it does not have the religious connotations of ad. Instead, it is based on the same calendar as ad but uses the term “Common Era” instead of “Anno Domini.”
Another alternative dating system is the Before Common Era (BCE) system, which is used to refer to the years before the Common Era. This system is similar to bc in that it marks the years before the birth of Jesus Christ, but it does not have the religious connotations of bc. Instead, it is based on the same calendar as bc but uses the term “Before Common Era” instead of “Before Christ.”
In conclusion, ad and bc are no longer used because of their religious connotations, lack of precision, and Eurocentricity. These dating systems are no longer appropriate for secular and academic contexts. Alternative dating systems such as CE and BCE have emerged, which are more appropriate for mainstream use. While ad and bc are still used in some religious contexts, they are gradually being phased out in favor of more inclusive and secular dating systems. As our understanding of history and culture evolves, it is important to recognize the limitations of traditional dating systems and embrace more inclusive and accurate alternatives.