Something like 15% of PS5 game sales are physical now and only 5-10 games managed to crack 100K disc sales in a recent year, last I heard.
Games are also exceeding triple-layer BluRay size now in many cases, and average internet speeds in the US are faster than BluRay transfer speeds. Since you've already had to install the games to internal storage since the PS3 at least (and the PS5 even has user m.2 SSD expansion), discs have just been an annoying extra step for a long time.
Also, online purchases are cheaper. Frequent sales happen, at steeper discounts than brick and mortar retailers ever have. Plenty of games were 50-75% off during the summer sale.
That being said, I've picked up a few on disc in recent years. It's a convenient way to share games in a household with multiple PlayStations and I've received some as gifts that way, since giving people a specific game as a gift in the physical world is still inconceivable to companies.
You also don't get Sony deciding to remove your access to already paid content. Bit difficult form them to physically come and steal it from your house, than change a row in a db.
Also in poorer countries there are physical game exchanges. You play a game and trade it in for a new one with some money. Digital only removes this. It also destroys the second hand game market.