Yes, and the prevailing counterargument at the time was, "But this time it's different! The fundamentals of everything have changed, because...internet!"

If you look at historical bubbles, and particularly at historical technology bubbles -- the South Sea Bubble, the Mississippi Bubble, the 1920s Bubble, the bubbles of the mid to late 1800s -- "This time it's different!" has been a pretty consistent pattern of denial. Typically there's a rational basis for the exuberance at first, but this onto this basis is piled a whole lot of speculative investment and fervor, wildly inflating valuations beyond the boundaries of plausible expected return.

Some of that mass irrationality has to do with easy access to capital, and some of it has to do with easy openings to capital markets. The latter is usually required to really kick a bubble into high gear. [So the operative question in this case is: what effect will the opening of private startups to public investment have?]

Are we currently in a bubble? Really, really hard to say. I don't feel qualified to make that judgment. But to answer your question, yes, most bubbles have at least a few naysayers who are bearish on the situation. But their voices tend to get drowned out, especially by those with interests in keeping the bubble going.