The legacy Bitcoin code had a maximum limit of 1MB of data per block, or about 4 transactions per second. There was also a common sentiment among Bitcoin Core developers that non-backwards compatible upgrades, commonly known as “hard forks”, should be avoided at all cost. This mindset severely limited the potential to introduce beneficial changes to Bitcoin, which were needed to prepare the protocol for mass adoption.
Although technically simple, the Bitcoin community could not reach a consensus on raising the block size limit, even after years of debate. In 2017, capacity hit the 1MB-imposed wall, fees skyrocketed, and Bitcoin became unreliable, with some users unable to get their transactions confirmed even after days of waiting. An average transaction fee of $50 took place in December 2017. As a result, Bitcoin stopped growing, and companies such as Steam and Microsoft began dropping Bitcoin, because it was no longer a cheap and reliable payment method.
In August 2017, a subset of the Bitcoin community decided to move forward with a proposed protocol upgrade, forking Bitcoin, and creating Bitcoin Cash by lifting the block size limit as a step towards massive on-chain scaling. There is now ample capacity for everyone's transactions on the Bitcoin Cash blockchain; low fees and fast confirmations are standard, and the network has been allowed to grow again.