You’re right about incentives to invest in infrastructure. Title II restrictions do nothing to help the situation, but removing those restrictions don’t help either. As I pointed out, it just provides more opportunities to exploit their clients on existing hardware. Profit provide an obvious motivation to do this and the only disincentive right now is the Title II restrictions.
As far as arguments that don’t hold water, there is no better example than “ISPs blocking content providers has never been an issue at all, only an imagined one.” The entire reason Title II restrictions were brought to bear was because of the 2013 lawsuit against Verizon brought by the FCC because they were pursuing these very practices. Verizon’s own council stated on multiple occasions “I’m authorized to state from my client today that, but for these rules, we would be exploring those types of arrangements.” You can find that quote, as well as many examples of ISPs blocking content for profit going as far back as 2005, on this page: https://www.freepress.net/blog/2017/04/25/net-neutrality-violations-brief-history