A lot of anime are produced with a single season that can run for only 12 episodes with 25 minutes each including intro and outro.

Some of those more popular ones do get further seasons but not on a yearly basis but there could be years between them. In case of konosuba the first season came out in 2016 with 10 episodes and second season in 2017 also with 10 episodes. Season 3 only released this year so quite a long gap between them.

However, the really popular ones are fairly overshadowing the general amount of shows being released. Just this season we got 54 new anime releases and 29 “continuing” according to MAL.

Some of those seasons are really strong like the spring season of this year in which a lot of very popular shows are released. Other seasons could then be fairly slow.

And since they are all produced to promote the source material that source material has to differentiate itself from the rest and draw people in quickly through the title. So you get titles like

• How Heavy Are The Dumbbells You Lift?
• God’s Blessing on This Wonderful World!
• Is It Wrong to Try to Pick Up Girls in a Dungeon?
• Reborn as a Vending Machine, I Now Wander the Dungeon

Especially the isekai (transported to another world) genre relies heavily on that to quickly explain what you can expect.

And then you shouldn’t forget that this is only that visible because more and more anime are actually making their way onto other platforms for the western audience.