I'm not saying that they all contributed, but the timeline in which we seem to find ourselves includes:

2014

• Tidal available in the U.S.
• Billboard and similar services begin calculating streams into chart products as equivalent to sales.

2015

• YouTube Music app released.
• YouTube Kids app released.
• YouTube Red subscription available.
• Apple Music launched to replace Beats Music.
• "Thinking Out Loud" by Ed Sheeran became the first song to pass 500 million streams.

2016

• TikTok released in China.
• UK votes to leave EU.
• "One Dance" by Drake became the first song to pass one billion streams.

2017

• Donald J. Trump sworn in as U.S. president, beginning an administration characterized by breaking norms, deregulation, and trade tariffs.
• TikTok available outside China.
• Pandora launches premium tier subscriptions.
• Facebook's massive investments in new technology (particularly in VR, dating, and workspace functionality) is stunted by Cambridge Analytical matter and accusations about fake news.
• Spotify begins major expansions in many counties.
• Microsoft suspends Groove Music Pass and directs listeners to Spotify.

2018

• YouTube Music becomes separate subscription service.
• YouTube Red rebranded as YouTube Premium.
• Self-contained Windows 10 version of iTunes becomes available on the Microsoft app store.
• Twitter algorithms begin hiding comments considered to detract from the conversation. (They can be revealed by "show more replies.")
• Spotify becomes a publicly traded company.

2019

• Amazon Music HD launched.

2020

• COVID-19 pandemic spreads worldwide with massive lockdowns closing clubs and concert halls, ending live touring, canceling music releases, and slowing recording. Millions die.
• Elections worldwide, including but not limited to the U.S. presidential election, seize enormous attention in social media.
• UK completes "Brexit" process and leaves EU.