RE: Our Plan for Onboarding the Masses

FWIW the actual founder was some anonymous and very erratic person named 'thankful_for_today'. You can read about the rest of the history here
I can't speak for Steemit Inc. Informally I would tend to agree with you they 'should' have done and should be doing more, but ultimately it isn't for us to say, as we have no authority over them. As far as witnesses, this is a bit of a learning and evolutionary process, as I will explain below.

To review a bit of history, Steem's design was derived from Bitshares, and Bitshares had workers in addition to witnesses (workers being equivalent to the SPS which is to be added in HF21). Under that model, the role of witnesses was narrowly to produce blocks. Other work needed to support the chain, including marketing, would be done by workers submitting proposals and getting direct funding. To simplify things when creating Steem, workers (as sell as another role called committee) were dropped and rolled into witnesses. Witness pay was set relatively high with the expectation that witnesses would carry out many of the funded responsibilities when were given to workers in Bitshares, which could certainly include marketing.

Under this model, in the first six months of Steem's existence witnesses did carry out a lot of marketing. I personally worked with another witness (who is no longer involved with Steem) and we paid to have advertisements designed and then paid to run them on various platforms. Other witnesses did similarly. This effort was somewhat successful and brought in the first real wave of users to start using the chain as well as helping to give Steem a higher profile among cryptocurrency investors.

Unfortunately it turned out that model was not sustainable. Despite some efforts to collect and track this information, the work being done and paid for by witnesses was not clearly identified any central database. Understandably, many stakeholders were frustrated, particularly given the steep price declines that happened at the time, about the amount being paid to witnesses and the lack of clarity about what was being accomplished. It is also likely that some witnesses were doing very little, though I both think this aspect was overstated and I also think that the appropriate recourse in that case is to vote those witnesses out or failing that, accept that other stakeholders don't agree with you and you have been outvoted. Nevertheless, that is only my opinion and not everyone agreed. Overall there was a lot of frustration resulting from the bundling of the worker/funding role into the witness role.

The outcome of this period was a change rolled into HF16 (pushed mostly by Steemit Inc, but ultimately approved by witnesses as well) which cut witness pay by 80% and refocused the witness role back on block production. It was stated at the time that workers were still likely not need in Steem because Steem already has a system to vote for funding, which is posts. People proposing to do marketing, development or other tasks could make posts and get rewards to pay for the work. There was some recognition even at the time that this would not be an ideal method for ongoing work, and the possibility was left open that workers could be added 'later'.

Well, fast forward to 2019 and it is by now clear that posting has not been a good method for funding work (such as marketing), and we are finally on the verge of adding workers in form of SPS included in HF21. Hopefully what gets funded using SPS will include some good marketing. That being said, Steemit Inc. is still by far the best-funded entity in the Steem ecosystem and if they don't also contribute to some marketing, then the budget for marketing, and the resulting marketing, may remain anemic. We'll have to see how it works out.

Do you not think it is time to change or remove the person responsible for marketing at Steemit Inc?

Let me repeat what I said above: We have no authority over them. As far as I know, at this point they don't even have anyone responsible for marketing, or if they do I have no idea who it is. They appear to want to operate on a shoestring budget and do the bare minimum of focusing on essential development and operating the steemit.com site, and while I may find that unfortunate or even unethical, there still isn't a damn thing I can do about it.

We can give them our opinions, which there has certainly been no shortage of. Apart from that, all we can do, really, is try to evolve Steem (such as with SPS) so that it can accomplish more things on its own without relying on Steemit Inc.