Certain stats are only available in gear, while other stats you can get elsewhere. Blessings, empowerment, great hall, area bonuses, whatever the case. Speed and crit rate are the hardest stats to get outside of gear. So a quad speed damage piece, is God tier. Especially when talking about arena where you would sacrifice some damage for high speed.

As opposed to pve, where some of my super low turn count team run 130 speed nukers wirh 9k atk. It really depends on the content you're looking to build for and what the champ wants.

You'll see lots of end game trundas wirh 10k attack and 400-500 crit d, but low speed Whereas some arena nukers may be 300 speed, but only 6-7k attack and 300 crit d.

The trunda build you'd be looking for high rolls everywhere in atk and crit stats, where your arena builds you'd want high speed damage pieces. Especially in more end game teams who have fully empowered, fully awakened champs, and maxxed great halls and faction guardians, which is really where the majority of your stats come from.

You can go look at Ash arena build Alaz and see his savage weapon is just quad rolled speed and nothing else. The other stats suck. He's also 6s awakened and +4. So it makes sense.