What is the history of $p < 0.05$ or 95% confidence? I'm wondering what the history of $p < 0.05$ or using a 95% confidence interval is. I know that more nuanced reasoning would argue that there is nothing special about 0.05 or 95% (I think decision theory offers guidance on what level of risk to accept) and that the usage of these numbers has more to do with "tradition" and doing what was taught in stats courses that themselves don't discuss why these numbers should be used well.
Wasn't it Fisher who suggested that $p < 0.05$ was small enough to discard a hypothesis, and mostly just as a suggestion rather than a rule? Or am I wrong on that?

See this historical article by Stigler (2008) in Chance, about Fisher's influence (as you suggest).
Much of early significance testing used the standard normal distribution.
As cut-off values get smaller than $-2.0$ there is rapidly diminishing tail
probability. So if one wants a relatively small tail probability without insisting on $z$-values too far from $0,$ it seems that
cut-off points around $\pm 2$ give a reasonable tradeoff between more extreme
z values and smaller probabilities. If one wants "round" numbers for
the sum of two tail probabilities, such as $0.01, 0.02, 0.03,$ $0.04, 0.05, 0.06,$ etc.,
then something near $0.05=5\%$ seems reasonable.

p = seq(.01,.1,by=.01); z = qnorm(p)
plot(z, p, ylim=c(0,.1))

