Yes, formal ones are frowned upon for sure. Fundraising must be one of the core competencies of a CEO as the driver behind making a groundbreaking idea come to timely fruition. No third-party should be able to tell that story better than the leader of the company.
Informal ones are not frowned upon, instead encouraged. As a trusted source removes some of the risks of false-positives and can improve the odds of not discarding a false-negative for venture capital firms, thus increasing the chance to find a real outlier.
Virtually anyone in Silicon Valley who has been successful in building companies, raising money and producing viable venture-style returns, and wants to vouch for you and your company strategy, can help provide pathways to capital.
BTW: Not all people who have made money and know a few venture-capital firms will fit the bill here, as prior success in monetary terms does not necessarily guarantee a knack for foresight that breaks the norm. The merit of money matters.
My directness and honesty (uncorrelated to the hype of populism) have led some top venture-capital firms to ask for my advice. They have asked me what I think about a certain company, and I have provided them with my opinion on the receiving side of helping startups to think bigger, aim higher and attach to macro, and how to “dress up for prom”. You would be amazed how many startups undersell themselves and think small, inclined to follow a path of least resistance to (subprime) funding, rather than the more difficult pursuit of upside from foresight.
On that note, the grand-scale sub-priming of innovation arbitrage, by the populism of uniformity of many wannabe-funds (in terms of returns) in Silicon Valley, has in turn sub-primed much of what is labeled innovation. Making it more difficult for all venture capital firms to find real outliers through a dense fog of subprime ideas. For a startup with a truly disruptive proposition therefore to raise venture capital, the careful avoidance of 99.4% of venture-capital firms with little propensity to support the upside of foresight requires careful and deliberate navigation of the investor landscape, and also requires a good understanding of the technology in question. Something a money finder/ broker (your words) is unlikely to possess.
Hence, to answer your question differently, instead of using a third-party, you should attract board-members who buy into the compass of your foresight and can help pave the way to the right investors (and future peer board-members), to build out the complete runway to the upside, not just a single round.