Among the items with RuneScape gold a large spread, players would want to flip those items leading to more competition which would reduce the spread consequently, thereby decreasing the effectiveness of flipping overall. However, a decreasing spread isn't a bad thing as it only affects the flippers.
They are just different when it comes to priority. Any and all suggestions have trade-offs, and this suggestion focuses more on the average player and less on the rich flippers. Not showing the spread and updating prices infrequently benefit the flipper.
With this in mind, I think it would be better for the game overall if we focused more on the average player, and maybe Jagex could do a poll to see if players care more about the average player of the flipper. I'm not anti-flipping.
Concerns about manipulating the market by OSRS Gold spiking and crashing prices are already concerns with or without this spread information, so if there are concerns about that, look towards other suggestions to control it while realizing that we can't make a perfect market while still allowing some trade freedom.
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