I have been a huge preamp user/buyer/seller over the years. I love a great tube preamp having owned at least 15 or so over the years. I have also built several very good tube preamps over the years. Today’s hybrid integrated amps are so good that I do not think sound quality is an issue anymore. The last two integrated amps I have owned keep pace with separates priced up to $12,000 - $15,000. In addition, you save the cost of one set of ICs and a power cord. Also, the short signal paths of a rightly constructed integrated coupled with eliminating the cable and connectors of separates is a potential sound quality enhancer!
I now own a John Tucker/eXemplar Audio made hybrid integrated with a tube preamp section. He included some nice upgrades (parts quality) I wanted and the result is wonderful. My previous Circle Labs A200 was also a hybrid design with tube front end that sounded very good.
So a preamp is certainly not a must if most concerned with sound quality. We have many good choices in integrated amps today!
For me the preamp was always the “heart” of a great system in the past. However if not into vinyl, than in today’s systems the front end dac/server combo can now play that role. I have found my dac is now the heart of my system.